Please visit our Sponsors
FAQs about genus Chromis Damsel Compatibility

Related Articles: Chromis Damsels

Related FAQs:  Chromis FAQs 1, Chromis FAQs 2, Chromis Identification, Chromis Behavior, Chromis Selection, Chromis Systems, Chromis Feeding, Chromis Disease, Chromis Reproduction, Damsel Identification, Damsel Identification, Damsel Selection, Damsel Compatibility, Damsel Feeding, Damsel DiseaseDamsel Reproduction

Chromis verator Jordan & Mertz 1932, the Threespot Chromis.

Fish Aggression, Green Chromis        9/6/19
<Hey Eric>
Out of nowhere my Green Chromis has decided to relentlessly harass my Orangeback Fairy wrasse to the point that it was only coming out to eat.
<Does happen; unfortunately>
The fish were fine for 17 months so not sure what triggered it. I put a mirror on the side of the tank and the aggression has basically stopped with most of the fish just staring at themselves. How long should I
leave the mirror on? A few days, etc? Any other tips?
<I'd try taking the mirror away in a few days... see what happens. Yes to other... using two nets, catch the offending Chromis and place it in a floating colander (plastic) for a few days... IF the aggression continues, trade it out. Bob Fenner>

Goatfish and Chromis Quarantine Questions – 12/03/12
Hi all,
Thanks for your continued knowledge and effort.  I have a bicolor goatfish and 15 blue green Chromis arriving in a couple days and had a couple questions about quarantine procedure.  They'll eventually be housed in my 1.5 year old ~260 gallon system with my blue tang, flame Hawkfish, melanurus wrasse, and ocellaris pair.
As far as the Chromis go, would you expect any social ill-effects from quarantining them in separate groups?
<Mmm, no. Better to do this than over-crowd... sort of like porridge/parritch and Goldilocks, too few and too many in a given volume often leads to/cause problems (aggressive/agonistic behavior)>
 I have an established 65 gallon with sand, rock, etc. that's been lying fallow for a year or so but am not sure whether it can handle the bioload presented by 15 Chromis (I'm assuming they'll be in the .75"-1.5" range).  If I split them up (say, 10 in the 65 and 5 in a 25 gallon glass bottom tank) do you think there would be any social concerns when I eventually reintegrate the multiple groups upon introducing them into the main tank after quarantine?
<Actually, they'll likely be "glad to be reacquainted" in the larger volume. This being stated, the commonly offered Chromis species that school show a strong trend toward "picking on" weaker individuals, reducing their numbers in time in captive settings; no matter what is done>
Thanks again,
<Welcome. Bob Fenner>

Damsel Compatibility... not    3/15/12
Howdy, I bought two yellow tail damsels (species recommended by Salty Dog as my first fish).  One is bullying the other making him stay up in a corner
<Very common behavior>

 (got them last Wednesday, so it's been a week).  I want to check on what the pet store said which was that what MIGHT happen is the bully will become the female and they will become a mated pair.
<Not likely. The one will cause the others demise>
  So one question I have is that if this does not happen, should I remove one of the fish?
<Yes I would>

 I have a 28 gallon bow front tank by the way.  My other question is, as I was reading through your articles and FAQs on damsels, I came across the Talbot Damsel and would like to add one to my tank.  I only have the yellow tails so far.  Thanks for the info!  Paul
<The Talbot may be sufficiently "different" to get along w/ the single Chromis. Bob Fenner>
Re: Damsel Compatibility, hlth.    3/15/12

Thanks for the response, that's too bad.  Well, if I'm going to move one out anyway, the one that gets bullied has some discoloration on his lips.
<I see this... very bad... Mouth damage in small fishes often leads to death>
I didn't notice it in the pet store, but I did right after putting him in the tank.  They seem more clear then white, but the pics show up white.
There is also slight white around both eyes that was not there before.  If you think it's a disease I'll take him out now, but the pet store thought it was an injury, so I've just been waiting for it to heal.  Thanks.
<Is very likely due to injury... BobF>

Re: Damsel Compatibility...     3/23/12
Hello again, I was hoping to give an update saying that all is well with my poor yellow tail damsel, but he stopped eating two days ago, and this morning I noticed a small red spot on his puffy lips (which seem to be a little puffier also) sort of like they are cracking open. 
<The end>
After reading your response that he may die from the injury anyway, I decided to just keep him around
<... needed to be separated>
 rather than give him to the pet store (kind of a way to let him die peacefully without even more stress of being recaptured and moved).
Also, I was going to move him to a 10gal refugium once I got that set up to stop the bulling, but now I'm wondering if this will turn to some sort of disease that will contaminate my tank, and should I just net him and flush the poor fellow?  Oh, and I also have some isopods, letting you know in case they might be making the blood spot.  Thanks, Paul.
<... B>
Re: Damsel Compatibility    3/23/12

Well, I'm saddened.  Is it worth trying to give him away or take him back to the pet store? 
My guess is no, but I'd rather him not die if there was hope for that.  I guess the lesson I learned this time is to listen to sound advice!  Thanks again.
<Doomed. B>

Marine Schools/Fish Cannot Read/Compatibility 10/20/10
Good Morning, hope you are all well.
<I'm still above ground, thank you!>
Can I pick your brains..
I was wondering, which species of small/medium (anywhere up to 3-5") marine fish naturally occur in groups during most of their lives. I'm aware of Chromis and Anthias obviously, as well as other damsels occurring in groups when young (although not when older of course!).. but there must be more to choose from?
<Let me stop you here, Chris. Species of fish that peacefully school/shoal in the wild does not necessarily mean they will coexist in captive systems.
When we try to do this with some species such as Yellow Tangs, the fish automatically go into a survival mode, that is they will defend an area that is a source of food and security, and in most cases only the Alpha fish will survive the battle. In the wild, there is no real lack of security and food sources to fight over. To have a chance at success, very large tanks must be used, and by very large tanks, I do not mean 240 gallon, but much larger than this volume.>
I have seen pictures of a whole big group of Orchid Dottybacks, but I presume the photo must've been of a brood being commercially reared... likewise I have seen tanks with myriads of Clownfish, but again I assume these were broods being raised.
<Very likely, and when young, safety in numbers is the rule. Your best bet, providing your tank is large enough, would be a school of Anthias or Chromis. You may want to read here.
Thanks in advance!
<You're welcome. James (Salty Dog)>
Re Marine Schools/Fish Cannot Read/Compatibility 10/20/10
Thanks James for that dose of reality and straight talk, always the best way :) I'll scrap all my silly plans.
<You're welcome, Chris. James (Salty Dog)>

And Then There Were Six, Chromis beh.  6/25/09
Hi Crew,
I recently added 7 small (3/4 inch) Chromis Viridis to my reef tank.
Then, on their second day of residence, I watched my LTA consume one.
<What they do>
He was still breathing, very slowly, as he went down. I figured that was the stupid one. ;-) Now I'm finding that the Chromis are sleeping with the LTA at night.
<Also natural... associate with stinging celled life to avoid fish predation>
Often as many as four of them in there among the tentacles. Is this common/normal/safe behavior?
<Normal yes, safe, no... Would "hang" in and about an arborose stony (likely an Acropora sp., perhaps a Pocillopora...) if you had one present>
They've plenty of nooks in the LR that they're eschewing. Maybe they know about the Stomatopod and figure the anemone is the lesser evil.
I've tried to get that darn mantis out. Traps have failed, hyposaline dips have failed. My LFS suggested leaving the rock out to dry for a couple hours, but that seems unlikely to work, in my opinion, and his
lair has some nice Porites sp. that I'd like to keep if possible. He's rather small, sub-one-inch and so far and hasn't wrought so much havoc. He walloped some hitchhiker Xanthids, but who's complaining.
I'm hoping that as he gets bigger he'll get hungrier for bait I periodically leave out.
I know, now, that the LTA wasn't the wisest addition. Purple tentacles, green and fluorescent green oral disk, about 6 inches across (on average), bright orange base. But I've noticed that he never quite closes his mouth. It's usually open about a centimeter. Is this gaping?
<Not necessarily>
He seems otherwise happy, hasn't moved since I buried him in the gravel, stands up at night and flattens out during the day. I'm a bit worried about allelopathy with the Euphyllias, Faviidae, Zoanthids, and Sinularia in there.
<Worth consideration...>
Thanks in advance,
<Bob Fenner>

Re: And Then There Were Six 6/27/09
Hi Bob,
Thanks for your input...
It seems that the Chromis had the last laugh. The anemone coughed out what was left of the fish as a whitish ball the following morning but not before busting its gut, so to speak.
<How they... egest>
I've noticed looks like a tear along the column with a small amount of what appears to be mesenterial filaments bulging out. I'm entirely not sure what to make of this, but I've read ( on WWM ) that there's a good chance that this will heal within a few weeks.
I'm a bit hesitant to remove it
<I would not>
to a hospital tank in this condition for fear of causing more damage. The water parameters all appear normal/unchanged: SG = 1.023,
<I'd raise...>
pH = 8.2,
NH4 = 0, N02 = 0 NO3 = 5 mg/l, Ca = 450 mg/l.
<A bit too high... what is your Alk, dKH?>
The nem's behavior hasn't changed and there's no apparent necrosis. So I've got my fingers crossed.
I have a couple other concerns. The Ctenochaetus strigosus has come to regard the nem as its toilet.
<Not unnaturally>
It repeatedly defecates on the anemone, which doesn't seem to mind/react, but this leaves a large pile of poo on the surrounding substrate that I have to very carefully vacuum out.
<Many anemone species... make a good part of their nutritional base thus>
Might an Anemonefish prevent this by keeping the surgeon at bay and/or cleaning up the area around the anemone?
<Mmm, yes>
Not to mention keeping the Chromis away. I've read ( WWM, again ;-) that they often do more harm than good but I'm wondering if this is a special case....
Finally, The shifting from my vacuuming has caused the nem to "float" to the surface of the substrate. It's still holding on but it's only got a grip on the surface grains and I'm afraid it will fall over when it stands up. The nem has never been willing and/or able to sink itself into the substrate, which is a coarse-ish crushed coral.
<Mmm, maybe put a semi-flat smooth-ish rock underneath>
The grain size varies from 1/8" to 3/8" with similarly sized shells mixed in. Should I try to dig a hole all the way down ( about 3" ) so it can get a good grip on the glass?
<... the rock>
Alternatively, I've considered taking a small polyethylene tub ( the ones that CD ROMS come in ), setting the nem in that, and sinking it into the gravel filled with soft fine oolitic aragonite. Alas, I learned too late about the disadvantages of crushed coral.
PS - Lighting = 4 x 39W 36" T5 HO. (2 6500K, 2 actinic). Water Depth = 12" Is this too weak, marginal, or ok for the nem?
<S/b fine>
I'm thinking marginal as it seems happy. It has never moved from where I put him a month ago. There's no apparent bleaching, but admittedly I have no idea how long it would take to show symptoms.
<Most captive systems are over and inappropriately illuminated intensity wise... Bob Fenner>

Puffer ate my Chromis! & Stocking question 4/3/2009
Hello from Florida and thank you for all you do for the saltwater keeper community, I cannot tell you how many times I have had your website's search feature save me from making utterly stupid mistakes with my tanks.
<Hi Dante, thank you for the kind words. This is Mike, also from Florida.>
A truly wonderful website and a most knowledgeable and helpful staff of experts. I tried to find answers for my questions through the web and by reading 4 different books but just can't seem to find answers, so here I am risking asking a stupid question.
<The only stupid question is the one that goes unasked.>
Here are my tank's basics:
110 gallon "tall" tank that is 48" wide and 30" tall.
120 lbs live rock
3" aragonite substrate
30% Water change every 2 weeks.
Ammonia 0
Nitrite 0
Nitrate 5ppm
Temperature 78F
Ph 8.2
Additives: CaribSea Purple Up
Wet/Dry Filter with bioballs
In the Sump:
Coralife 125 Needle wheel skimmer
1.5 Kg of Seachem Denitrate
1 liter of Seachem Purigen
1 liter of Marineland Black Diamond
1 Polyfilter.
<Thank you for the detail, it makes it much easier to troubleshoot problems.>
26" Zebra Moray Eel ((Gymnomuraena zebra)
3" Porcupine Puffer (Diodon holocanthus)
5" Yellow Tang (Zebrasoma flavescens)
4" One Spot Foxface (Siganus Unimaculatus)
1- 0.5" Blue-Green Reef Chromis (Chromis Viridis)
1-1" Blue-Green Reef Chromis (Chromis Viridis)
Running for 4 months
My fish are quarantined by my LFS in a separate system as a favor from the owner.
2 weeks ago, I added 15 Chromis weighing the possibility of adding too many with the safety numbers provide from the Puffer and I ended up wrong.
I took the risk because in my opinion there just wasn't enough activity in the tank. Puffer ate 8 of them and gave heart attacks to 5, leaving only 2, one of which is one of the smallest ones. The 2 that are left swim in front of the puffer and all around him and he doesn't seem to care. Any insight as to why he has spared 2 of them?
<He hasn't gotten around to eating them yet. Do make sure you are feeding your puffer the appropriate foods, it can help with aggression issues.>
I really like the variety that the smaller fish bring, could I add 2 or three aggressive damsels, or would they also become lunch?
<Depending on the size and\or temperament, it is a definite possibility.>
Additionally, I cannot decide on what to finish stocking with. I like the Niger Trigger but it gets too large and would eat the Chromis, a Maroon Clown would beat up the Chromis or damsels (if I add them), a Coral Beauty angel or fire angel seem too delicate, Heniochus butterfly also seems too delicate. Another tang would fight with my yellow.
< I agree with, though a large enough Maroon Clown could probably hold its own, they are more aggressive than other Clowns and get to 6" in length.>
Those are the fish I've been looking at. Is there any possibility that any or some of them could work out well? I do not want fish that won't be active, hide, sit on the substrate all day, get too large for me to properly care for them, will eat my fish, or will fight with and kill my fish. It seems I may have to get rid
of the 2 remaining Chromis and not get damsels to go the predatory fish route, or be super diligent and take a risk by going the delicate fish route.
<I would return the Chromis (if you can catch them)>
I am responsible for my current and future fish for being taken from the ocean and I want to provide the best care possible. Any suggestions at all would be wonderful. I am stumped, please guide me and help me avoid making a mistake with stocking my fish tank. Any other suggestions you may have about my setup would certainly be welcome.
<Any tankmates for a Puffer need to be able to defend themselves, unfortunately, this limits what you can put in with them. I think a larger Maroon Clown, perhaps a pair, without an Anemone would be appropriate
I am not fond of Damsels personally, I find they get too belligerent over time to anything, up to and including you.>
Thank you so much, and you have my greatest respect as the experts that you are. Thanks again for
providing such a great resource to us all.
<My Pleasure, do write back if you have other questions..

Re: Puffer ate my Chromis! & Stocking question 4/3/2009
<Hi Dante>
Thank you so much for such an incredibly quick response. I will try to remove the Chromis today and spare their lives. I will also have my LFS order me a maroon clown to start the quarantine.
<Very Good>
Just one more question. Am I correct in assuming that the other possibilities are out? In other words, the trigger gets too large and aggressive.
<Too big, Yes>
The coral beauty, and Heniochus are just too delicate & high maintenance, or would large ones likely do well? Would another tang would probably just create conflict with my current one, regardless of size?
<Not so much delicate or high maintenance, although some of them are, but more apt to get beaten up by the Puffer. The problem with adding another Tang is it will get larger - thus overcrowding your tank.>
I've read countless profiles and compatibility info as well as FAQ's and possible diseases on these species and that's what they seem to convey. I would really like more color and movement in my tank but don't want to doom a new addition due to my ignorance. Thank you so much for your help and support.
<My Pleasure>

Acute Chromis Hierarchical Aggression -- 02/28/09 I am hoping you can help me resolve this problem in my 150-gallon Oceanic half-round tank. <<I shall try>> I am getting conflicting advice. <<Not uncommon in the hobby 'and no different here>> The current inhabitants are 3 blue-green Chromis (viridis), a Foxface Rabbitfish (Siganus lo), a yellow-bellied blue hippo tang (Paracanthurus hepatus), <<The dimensions of such a tank as this really don't afford enough room for this fish>> a 12-line wrasse (Paracheilinus tetrataenia), a false percula clown (Amphiprion ocellaris), a diamondback goby (Valenciennea puellaris), and one skunk cleaner shrimp, plus assorted hermit crabs, snails, bristleworms, etc. After 1-1/2 years, the Chromis seem to have fallen into a pattern noted on your site -- one Chromis became dominant and started harassing the other Chromis to death. <<Very common, yes'¦ Though I think when fishes are provided with adequate shelter and sleeping spaces, enough of the right foods, an environment of adequate size/composition that's free from interspecies aggression 'then such 'intraspecies' aggressions are lessened>> I originally had five Chromis; I can now only find three; and two of those seem to live together in a small nook between two pieces of live rock. <<Mmm, indeed'¦ Even among such 'schooling' species there are ultimately pairings at which time 'territories' can become an issue. And if the tank is too small to accommodate such 'then there is likely to be trouble for the other fishes, conspecific or not>> In fact, I have not seen those two come out of that tiny crevice in 3 weeks. I have been feeding them by hand (otherwise they would surely starve). I do believe the big Chromis is to blame. I had never seen any other of my tank's inhabitants exhibit aggression (The tang sometimes seems to harass hermit crabs, picking them up and dropping them, but that is it.). <<Agreed 'the problem here is interspecific>> I have also noticed that, now that there is no 'school' of Chromis, the bigger fish (the Foxface in particular) spend less time in the open, and the Foxface spends more time at the back of the tank in his 'stress' color (brownish and blotchy) than before. <<This behaviour is also very likely due to aggression from the Chromis'¦or the Tang>> Water parameters are all good -- no ammonia, no nitrites, although nitrates peak at about 40 just before the bi-weekly water change. The 'service' that helps take care of my tank said to add more Chromis; <<I disagree>> both your site and the LFS advise that that will likely cause the cycle to repeat itself as the existing bully harasses the newcomers too. <<Agreed 'along with increased stress to 'all'>> The LFS says to remove one or more of the Chromis (a real burden given all the live rock). (While I tend to trust this LFS -- the owner has a degree in marine biology -- the measure seems pretty drastic.) <<I much agree with your LFS'¦reducing the Chromis to a single pair would indeed help>> The LFS also proposed adding 3 Lyretail Anthias (two female and one male) as new dither fish. <<I would resolve the situation with the Chromis first'¦and then see how the other tank occupants react before adding more fish>> The service concurred, but said not to remove the Chromis if I add the anthias; <<'¦!>> the service says that adding the Anthias, together with rearranging the live rock, would change the tank dynamics, distracting the dominant Chromis and allowing other Chromis to leave their nook. <<A poor and certainly 'temporary' fix in my opinion. But then perhaps they can sell you even more fish to repeat the cycle once the Chromis establish their new territory>> Now I have run across a few posts in other websites stating that Anthias may have some of the same hierarchy issues (intraspecies harassment that leaves only one alive) that my Chromis had. <<Not 'may''¦they 'do have' such. And though there are some species of Anthiine that are easier to keep in social groups than the Chromis in my experience (e.g. -- Pseudanthias bartlettorum), I would not add such to this tank, with the Chromis present>> As you can tell from my (hopefully conservative) stocking thus far, I have tried to stick to 'easy' and 'easy-going' fish. <<Hmm'¦then why a 'Damsel' selection I wonder>> I want a happy tank; no dead fish or even unhappy fish. But the advice I am finding is hopelessly conflicting. <<And I'm sure I have no doubt added to this>> And the two subordinate Chromis cannot continue living in a crack between two rocks, so current conditions are not sustainable. What would you do? <<Try to remove/reduce the Chromis population. You could try a pair, or remove all/all but one'¦but I would NOT add more Chromis to this tank. Regards, EricR>>

Re: Acute Chromis Hierarchical Aggression - 03/01/09 Thanks for your advice (which seems sensible). <<Quite welcome (and thanks...I think [grin])>> I am sorry to hear that the tang will be short on swimming room. <<Yes indeed'¦ All Tang species require more room than most hobbyists realize. These are active and wide-ranging fishes compared to most of the 'reef' fishes we keep. And Paracanthurus hepatus is a very robust very active species, and for lack of a better word'¦a bit 'twitchy' as Tangs go, in my experience'¦that requires as much room as some of the larger species for its long-term physiological and psychological well-being (hundreds of gallons in a linear configuration to optimize swimming)>> Before I got it, I tried to make sure the tank size (150 gallons) and the width (5 feet) were going to be adequate; <<It is my opinion that even 6-feet is marginal/the minimum for this species>> that was thought to be enough according to every source I consulted (e.g., Scott Michael, Reef Aquarium Fishes, which says 100 gallons is adequate). <<Ah yes'¦ And admittedly my name lends little weight to 'my' argument to the contrary. But more than three decades of seeing this species ultimately fail in typically sized home aquariums (less than 300 gallons), or at best live miserable lives frantically hiding at the slightest movement, or relentlessly pacing along the glass, as well as developing behavioral/social disorders to the point of attacking other fishes (I recall one instance where a hobbyist related to me how a P. hepatus suddenly went 'berserk' and killed the other fish in the tank) has led me to believe what I say here. And while there are almost certainly other contributing factors in all instances, they were/are only exacerbated by the 'too small' environments in which this fish is most often kept>> My research also showed the Chromis to be "peaceful" (even if it is a type of damsel) and it is often described as non-aggressive. <<And what does your experience with them now tell you? I will submit that you can always find two sides to an argument'¦and determining which best applies to you/your situation can be difficult. I do wonder if many of these categorizations are based on observations of the fishes in the wild'¦where environmental and social conditions are optimized'¦>> More examples of conflicting advice -- or perhaps fish of the same species with different personalities (or reacting to different circumstances). <<The former is a possibility'¦but I think the latter is more of a probability. Size/configuration of captive systems can certainly influence behavior/social development'¦and the addition of even one more foot in length to your system could possibly make a significant difference in your fishes behavior>> I will remove the bully chromis; rearrange the live rock (adding more) to make sure there are lots more hiding places; <<An excellent decision'¦but, do be careful not to limit room/swimming space for the Tang (a bit of a Catch-22 here)>> and watch carefully for signs of stress. A real shame that the tang may end up needing a new (bigger) home. <<Is a certainty in my mind'¦and though it may be a couple years, I think it will also become evident to you>> Thanks again for your help. <<Happy to share. Eric Russell>>

Question About Genus Chromis of Different Species, sel., beh.    1/10/09 Hello, <Wes> I've recently set up my new tank and am looking for the last couple of fish to add to it. I have two Chromis virdis currently and would like to add a couple more fish from the same genus, but, perhaps a different species so that there will be some more color to the tank. Related to that, I have a few questions: <How large is this tank? Shape?> 1) Will Chromis from different species school together or is it best to stick to just one species? <Some species do associate in the wild and in captivity, particularly with C. viridis> 2) I've read that Chromis cyanea are difficult to keep and that they get mean when they get older. <Mmm, these are relative terms/measures... I rate C. cyanea pretty low relatively on being difficult to keep and mean... amongst Damsels, marine fishes period... maybe they'd get a 3 or so on a scale of 10 IME> I've found Chromis insolata and Chromis limbaughi to be listed as peaceful and easy-to-care for fish, but wanted to see if you have any further input on these different species. <Have seen and kept both of these... and they are actually slightly both higher on the improvised scale mentioned above... and not great schoolers to boot> As always, thanks in advance for all you folks do! Wes <Again... I do wish you had mentioned the size, shape of this system, the other livestock, perhaps the gear... I might look to other families of fishes period to mix with the present Chromis... perhaps Anthiines, Apogonids... Bob Fenner> 

Chromis viridis Compatibility -- 7/30/08 OK so I think the website is great. I thank you for your many hours dealing with those who appreciate, and those who don't appreciate your efforts. In fact it is so interesting that I probably spend way too much time reading the posts. Oh no, now that I think about it I am probably addicted. Enough of my personality quirks and on to my question about compatibility. I have a well established 90 gallon tank with live rock and a DSB. The live stock consists of 2 mated perculas (the female is about 2 inches and the male is half that size), a 2 ½ six line wrasse with personality, a 3 inch purple tang, and a 3 inch lawnmower blenny. There are also a bunch of miscellaneous snails, a leather coral and a bubble tip anemone who over the many years I have had saltwater tanks has split into 6 individuals. (It has split each of the three times that I moved to a larger tank and I just don't have the heart to give any of them up.) The tank is very stable and everyone seems to get along very well. <Sounds good thus far> Now to the question, since I apparently can't just leave well enough alone. I am thinking about adding a school of 5 small to medium sized Chromis viridis to add a interest and to create a more action in the upper portion of the tank. I would add all 5 at the same time after their quarantine period. What do you think about the compatibility of the livestock? <That they'll go in here just fine... add some nice color, motion to the mid/upper water column> Am I just asking for trouble or do I have a reasonable chance of success? <The latter> As always, your wisdom is appreciated. Mark <Mmm, am hoping for the wisdom... with further age. Bob Fenner>

Chromis aggressive - 07/19/08 We have four green chromis and two purple (look black) Chromis. We've had them all for over six months, no problems with them or with the other fish. All of a sudden one black chromis is continually chasing the other black one, they were both added to the tank at the same time when they were small. Is this an indication they might be wanting to breed, or?? One has the other hiding to get away from it. Marilee <Mmm, though, amongst Damselfish genera, species, Chromis tend to be "more mellow", there are individuals who are at times quite aggressive... Particularly when kept in too small settings, in too small groups... I'd likely trade in the more agonistic one here... unless you have room, desire to add several companions. Bob Fenner>

Re: Chromis aggressive  7/19/08 Thank you Bob for your prompt reply, I thought that we might have to have the aggressive one returned. Fortunately the store we deal with is always willing to accommodate. We weren't sure if this could be a mating ritual but obviously not. Marilee <Ahh, might be mating-related to degree... But, best to return. Cheers! BobF>

Chromis feeding  7/3/08 Hi guys and gals I have 135 g tank with 100lbs of live rock. Tank is about 8 yrs old. I am thinking of buying 5 chromis. For fish I currently have a yellow tang, Foxface Rabbitfish, royal Gramma, clarkii, and a mandarin dragonet. My question is this: Will the 5 Bluegreen chromis deplete the population of copods for my mandarin? <Mmm, not likely... they spend most all the time near the surface... the copepods et al. that Callionymids are interested in are at, in, near the bottom> I am feeding phyto and see copods on the glass all the time. I just love that little guy and would hate to add fish that would be detrimental to him. I checked your FAQ's but couldn't find this answer. Thanks so much for supplying this service. When I get on here I just read ( and learn) for hours. Cindy <Good. BobF>

Hawk attacked Chromis, 6/11/08 Hello Chris Again , <Hello> Well, "when it hits the fan ~ it hits the fan!! <Does often seem to go that way.> Chromis was placed in the main tank yesterday, so as to provide the QT for Lady Clown . Hawk attacked her, resulting in me placing her floating in a colander through the night for protection. Slowly released her today, and what do you know, hawk took a chunk from her side. I have her harbored in a tank within the main tank and just shut the lights to let it rest. Now two hours later, she is labored breathing, head down, tail up, and I forgot to mention, diminished eyesight. Again, I come running to you for advice. Don't forget, she is approximately 12 y/o, been through a tough 2 days, now with injuries-is she so stressed that it will kill her? Heart broken again! Donna <I would leave the lights off for a day or two, hopefully give the hawk a chance to get accustomed to her. A fish that can take the rigors of aquarium life that long is nothing if not resilient, it's probably just stunned a bit right now. If she does not improve or begins to worsen you could try to put her back in her old tank, hopefully the clown will be ok with this and give her a chance to recover.> <Chris>

Chromis Behavior with the Chromis Shrink Adam J. (Bullying?) 3-23-08 Hi Crew, <<Hello Jason.>> I'm having some trouble with my blue-green chromis school. <<Lets see what I can do to help out.>> I have 5 chromis in my 90 gallon (+30 sump) reef, sharing space with a golden hogfish, 2 ocellaris, lawnmower blenny, purple Pseudochromis, and a flame angel. <<Those are some potentially boisterous mates for the, most of the time, mild mannered chromis.>> I am dithering on whether or not to remove the chromis, but before I do, I want to seek advice on their behavior. <<We'll see what insights I can provide.>> I've had the group of 5 for almost a year. Until recently, all seemed pretty happy, but over the past few weeks, things have gone downhill. <<I am curious to know if any of the aforementioned tank mates were introduced during that time?>> They mostly hang out in the corner of the tank and don't swim around. <<A sign they are insecure with their surrounding'¦perhaps some bullying going on, either externally (from tank mates) or within the shoal itself? Any observations on your part that can attest to this or refute it?>> Worse, two of them seem to have stopped eating over the past week. <<Assuming water parameters are acceptable and that they [chromis] are in otherwise good care/health this bit of circumstantial evidence leads credence to my assertion that there may be some psychological issues occurring, specifically bullying.>> One of them has developed a bizarre nocturnal behavior -- rapidly swimming around the walls of the tank repeatedly. <<**Insert above comment here as well.**>> Not sure what's going on. <<See above, can you lend any observations that would help me to better 'diagnose the issue.'>> The tank is well established and stable -- pH 8.0-8.2, SG 1.025, 80F, 0 NH4, 0 NO2, 7 hour photoperiod, ozone, ORP 450mV. All other fish are acting normally; my clownfish even started spawning in early February! <<With spawning often comes aggressive 'patrolling' of said breeding areas.>> I feed all the fish Pro Reef flakes once or twice a day, sometimes supplement with frozen Spirulina or Nori. <<Try something that simulated/replaces the chromis feeing on zooplankton. Mysis shrimp or finely chopped krill/clam meat.>> None of the other fish are bullying the chromis, though they seem to bully each other occasionally. <<You could me missing, specifically during the night hours.>> Any advice? <<Rearrange the aquascape, attempt to isolate some of the "bulliers," or if all else fails remove the chromis. You are pretty full for a 90 gallon, at the least there is some psychological crowding going on.>> Thanks as always! <<Anytime.>> Jason <<Adam_J.>>

Second Visit; Chromis Behavior with the Chromis Shrink Adam J. (Bullying?) 3-23-08 Hi Adam, <<Hello Again Jason.>> Thanks for the prompt reply. <<We do our best.>> My intuition is that bullying is going on. <<Mine as well from what I gathered in your last email.>> I did add one other fish after the chromis -- the flame angel. They don't seem to notice each other. In fact, the chromis never seem to be troubled by the other fish, as they stay near the top and the others tend to occupy the rockwork areas. <<It may not be their choice that they are not occupying the rockwork.>> When feeding, the chromis usually get the food at the top of the tank, and the others let it float down some, or they all just crowd around. The chromis are generally passive fish, but the most aggressive eaters in my tank. The chromis don't encroach on the Clownfish's territory, and I've never witnessed the clowns going after them (clowns sometimes scuffle with the hogfish). There is intra-shoal bullying for sure. <<Normal, hopefully the 'aggression' is spread around and not focused on a single individual.>> Two of the chromis seem to be the more dominant, two semi-aggressive, and one completely passive. The most passive (ironically, the biggest) has not eaten much if at all the past few days. <<Try putting some more variety into their diet with the suggestions I sent you in the prior email.>> The others all have eaten when I feed, at least usually. At night, they mostly retire in a corner behind the rocks, though one is now doing the rapid swimming and another sleeps in a top corner of the tank. The bullying takes the form of chasing. <<Yes'¦an attempt to clear the aggressors territory.>> It usually does not happen when they are eating (they are too focused on eating!), but soon after the aggressives will chase the others around some. I have a 10g quarantine tank all set and empty. Should I temporarily remove the bullies or the ones that aren't doing well? <<It is certainly worth a try.>> I need to mess with my rocks soon, anyway, to catch a Zoanthid-eating crab! <<Good luck with as well.>> Thanks, <<Anytime.>> Jason <<Adam J.>>

Re: Centropyge loricula'¦Reef Acceptable? (Oh Yes!) -- 12/27/07 Eric, <<Justin>> Thank you for the quick and helpful response! <<Quite welcome>> I would like to follow up by asking another question in regards to the overcrowding and/or bullying that may cause abnormal behaviors. <<Mmm, okay'¦but is pretty straightforward>> I currently have one yellow tang and two blue-green Chromis in my tank. However, I had planned on adding 5-7 more Chromis and two black Ocellaris clowns to the tank before considering the flame angel. <<I see>> Would my current livestock or the future of it be a problem with overcrowding and/or bullying? <<These fishes/this order should all be fine with the angel. I do have some small concern re the group of Chromis in this size tank (75g)'¦in my experience, they're not nearly so docile toward conspecifics as many seem to think>> Thanks again, Justin <<Always welcome. EricR>>

Chromis... mixing species    12/5/07 Thanks for all you guys do, I've learned a ton from what I've read on your site!! My question is about Blue chromis (chromis cyanea), blue/green (chromis viridis) and blackaxil chromis (chromis atripectoralis). How would these fish react if mixed in a 150 gallon tank, such as 3-4 of each. Would they school together? <Doubtful> Do they have interspecies issues? <Might well be> Thank you in advance for your advice!! Scott <I would stick with at most two species here; better just more numbers of individuals of just one. Bob Fenner>

Disease or Injury? Chromis aggr.  -11/27/2007 Hi there, <Richard> I wonder if you can help. I am a great fan of your website. Every time I google something marine-related, your site comes up! <Obviously... we both have good tastes!> I have a 35 UK gallon tank with 2 ocellaris clownfish (juveniles, been in tank approx 1 month). The only other inhabitant is 1 juvenile yellow tail damsel (Chromis xanthurus). <Mmmm> Against my better judgment the LFS advised me to try 3 damsels before clownfish as they were more hardy. I have observed this damsel systematically 'bully' the other two damsels to death over the course of the next few weeks (first one stayed permanently under a rock and lasted 2 days, second one then did exactly the same thing but lasted about 10 days). I did go back to the shop to look for advice (unfortunately too late for the damsels). <I'd return this fish to your stockist> The 2 clownfish I bought appeared to be buddies and began swimming together and interacting a lot when first introduced. They also appeared to hold their own against the remaining bully damsel. However, this morning I noticed that the clownfish were separated and that one of them is hiding under a rock (in similar fashion to the damsel victims). The other clownfish also appears to be quite subdued i.e. not moving position very often. This is in contrast to the damsel, who now investigates them often and fake charges them, shoots around the tank and generally looks like he/she owns the place. <Does> One of the clownfish has now developed some marks on this head. There are about 3 or very small white marks that stick out a little bit. He also did not feed or move out from under the rock when food was introduced. As always appears to happen to me, I didn't get to see how this happened and I am surprised that this mark has just appeared. I am at a loss to figure out whether it is some sort of abrasion (possibly from the bullying damsel) or whether it is some sort of disease? If it is a disease I am surprised I didn't notice it growing slowly? <This is much more likely physical trauma marks... and/or simple stress> However, I note that Brooklynella is mentioned on your website quite a bit, is this possible. <Not likely. Would have shown much earlier> There don't appear to be any marks on the gills. My reading for the tank are 0 for Ammonia, Nitrites, Nitrates and salinity on 1.024, ph 8.3. Any pointers as regards how to diagnose whether this is bullying related or a disease is appreciated. <Remove the Chromis> I was considering taking the bully back to the LPS anyway and I am just suspicious that at least one clownfish is showing the same behaviour the 2 bullied damsels exhibited. I did recently introduce some marine turbo snails, can they harbour fish diseases? <Can, but again, rare... the bullying Damsel has to go. Stat. Bob Fenner> Richard

Stocking 300 gallon tank The "Chromis Factor" (Keeping a Large School of Chromis with Aggressive Fish?)  11/26/07 Dear WWM crew, <Scott F. at the keyboard today!> Just set up my 300 gallon circular tank (see attached pic), it has a 72x20x20 refugium attached to it (about 150lbs of live rocks with live sand) plus a closed mechanical filtration system (a Jacuzzi filter).<<Will need more... RMF>> <Nice configuration.> I have a Hippo tang 4"-5", Clown trigger 3", Pink Tail trigger 4", Tomato clown 3" and a Lunare wrasse 4"-5" which I'll be transferring to this tank but First. I would like to add a school of Chromis viridis. I actually would like the school of Chromis to be the focal point of the tank, so how many should I add?? Twenty or so? <Well, I'd be inclined to go with a smaller number, like 12-15, but that's just my gut feeling. Your aquarium could probably support 20 if well maintained. I'm not a huge fan keeping large schools of these types of fishes, as you will see shortly.> Will they be compatible with all those aggressive tankmates? <To be honest, you might see some attrition among the Chromis. The Clown Trigger and the Lunare Wrasse are of particular concern to me, not to mention the possible hierarchical issues that can occur among the Chromis themselves. It's really your call here, but I would not be fulfilling my promise to you as a fellow hobbyist if I didn't warn you of possible problems. Large groupings of Chromis always seem to work better on paper than in practice, in my experience! There always seems to be some factor (disease, possible predators, interspecific aggression, etc.) that arises when keeping multiple damselfishes. Believe me, I've lost quite a few in various attempts over the years! Throw some aggressive tankmates into the mix, and the odds for success decrease further, IMO.> Would also like to add a Harlequin Tusk after the Chromis and before the transfer too. Will the Tusk get along with my Lunare? <Man, this isn't really helping me feel better about the Chromis! As mentioned above, there will no doubt be some "issues" with the Chromis. As far as getting along with the Lunare, it really depends on the specific individuals involved. In a sufficiently large aquarium, your odds of success are far greater than they would be in a smaller system. Supplying ample territory for each fish is important.> I'm also going to add an Kole tang to take care of algae so will that be ok with the Hippo tang? Thanks a lot, Bill <I don't think that you'll have much trouble with the Kole and the Hippo. They inhabit different ecological niches, and should not have an real difficulties. In the end, though-I'd rethink the Chromis issue. With some interesting larger fishes, why "clutter" the system with these fish, or risk them becoming someone's appetizer? Just my opinion. Good luck! Regards, Scott F.>

Nice! But maint.?!

Chromis Compatibility   9/2/07 Dear Bob & Crew, I trust this e-mail finds you all well. <Yes, thank you Mike> I quick description of my set-up followed by a quick question, if I may. Set-Up: 72gal. Bowfront with 80lbs. LR and Reef Sand, Hang-On Skimmer, Eheim Pro ll Canister Filter, 2 x Maxi-Jet 1200 Powerheads, Heater and 260W total of Actinics and 10,000s on timers. Corals: A few Leathers, <Mmm... Alcyoniids are large producers of biologically important molecules...> Glove Polyp, Green Star Polyp, Colt, Frogspawn (mislead by LFS on the Frogspawn - ok once I found it an out of the way spot) Inverts & Misc.: Sea Urchin, Serpent Star, Blood Shrimp, 3 Snails, a Conch, some MIA Hermits, 2 Feather Dusters Fish: Purple Tang, Coral Beauty, Pixie Hawkfish and 2 x A.O. Clowns (Coral Beauty and Hawk might be near fully grown while Tang and Clowns are about halfway there) I used to have another Cleaner Shrimp (the Hawk?) and a nice red Star Fish (the Hawk again?) <Maybe the former, doubtful the latter. Many stars are problematical in captivity> Now to my question. I currently have 6 nice Blue Green Chromis schooling around in my 20gal QT since last week. As I try to understand the order of these things, I probably should have added this type of fish to the display tank earlier in the stocking order, however, here we are and I would like your opinion on whether or not it's just too late for these smaller fish, or might they be ok if introduced to the 72gal. community now. If not, they seem to be enjoying life in the 20gal. just fine and I suppose I could leave them there, but I thought this little school would be a nice addition to my larger tank. That is, unless they will just become moving targets for the Hawkfish and/or maybe the Tang. Unlike these two fish, the Chromis seem quite innocent and harmless. I would not like to throw them to the wolves. Thank you for your time. Mike <Chromis do set up their own social dynamic... I do give you good odds with the mix of life you already have here... I would place them all at once... earlier in a day when you can be home to remove one (possible to likely) should there be trouble. Bob Fenner>

Re: Chromis Compatibility   9/4/07 Good day Bob and Crew, Thank you very much for taking the time to respond to my e-mail. <Am glad to share with you Mike> (wouldn't you know, I just found my original Blood shrimp K.O.'d lying on the sand. Dead shrimp #2. I think I might need to find a new home for that $%^&* Hawkfish, however, this is not the reason for this e-mail) <Cirrhitids and shrimps do not mix> As you have put my mind at ease regarding my original question / concern, you have put another question in my mind with one of your remarks, which I know by now you do not make without reason. When I mentioned that I had "a few Leathers", you wrote "<Mmm... Alcyoniids are large producers of biologically important molecules...>" <Yes... sorry for the interjections... from lingua Latina meaning to throw in-between> I have, according to my LFS, two different "Finger Leathers" (although if one is a "Finger" leather, the other should be called a "Hand" leather), and I have an Umbrella. <What is this last?> I did some searching on-line to try to figure out what you meant by your remark, however, I think I might still be missing the point. Would you mind explaining the significance of that remark, or perhaps, point me in the right direction? I would like to make sure I understand it correctly. Thank you Mike <I do apologize for the lack of completion, clarity. I am/was referring to this family of soft corals (Alcyonaceans) propensity for production of mostly terpenoids... and their capacity for mal-affecting the behavior and physiology of mostly other cnidarians. Please read here re: http://www.wetwebmedia.com/alcyoncompfaqs.htm Bob Fenner>

Compatibility/Lost Chromis'... mis-stocked FOWLR   8/10/07 Dear Bob, <James with you today.> This past week I added 5 Green Chromis to my 180 FOWLR tank.. After the fist night all but 1 disappeared. Found a second in the bulk head area of my tank but saved him only to see him die off from being hurt. <Have you looked on the floor behind the tank? You do have fish in your system such as the Tomatoe Clown who, once settled in, become very territorial and can/will chase other fish from it's claimed territory, and if no top is present, the Chromis' will jump to escape, sort of like from the pan to the fire.> The one remaining has survived perfectly for a week so I decided to add 3 more to the tank which were larger then the previous batch. Everything was fine past the first night and next day the 3 I added disappeared also. Everything else I add is surviving and the small original chromis is still alive and well. I am BAFFLED. I have in my 180 gallon tank: 2 Perculas, 1 Tomato Clown, Black Clown, Yellow Tang, Porcupine Puffer, <A poor choice here if you have inverts in the tank.> Porkfish, <The Porkfish is a known eater of starfish.> Copperband <Another fish that doesn't belong with this gang. Hard enough to acclimate as it is.> Pearlscale Butterfly , 2 Pajama Cardinal, Bicolor Parrotfish, Coral Beauty angel, Purple lobster, Green Brittle Star, Blue Linckia star, Bahama star, 4 Pincushion Urchins, <The urchins may/will be in trouble with the Porcupine Puffer at the dinner table.> 2 feather dusters, <These will more than likely suffer from the Copperband.> Flame Scallop, <Another poor choice of invert, not long lived, especially with it's tankmates.> 8 Peppermint Shrimp, <Good meal for the puffer.> Striped Damsel, 1 Green Chromis, Horseshoe Crab <Good sand stirrers but need to be fed occasionally unless your substrate is teeming with critters.> Water perm: salinity 1.028, nitrates 0 nitrites 0, ammonia 0 |20 gallon refugium, 30 gallon trickle filter, 3- 250 MH with actinic bulbs on a natural light cycle. <Keep looking my friend, I'm sure you will discover them or what's left of them. Before purchasing fish and/or inverts, do research their compatibility with their future tankmates before buying. James (Salty Dog>

The Blue/Green Chromis Blues...  6/20/07 I have been looking into purchasing 5 blue/green Chromis for my 72 gallon FOWLR tank. After much research, I learned from about half the people that tried to keep Chromis that one of the Chromis will become dominant and kill off the rest. <An all too common occurrence. Dominance hierarchies often occur, and the subordinate members of the group bear the brunt of the aggression. Also, in general, these fishes do poorly after collection, tend to ship rather poorly, and are susceptible to diseases that can weaken them before they ever make it to your aquarium.> When I went to the fish store I asked the clerk about this and he said he had never heard about it and that since these Chromis belonged to the same school, I should have no problem. <Interesting theory, but I don't think that the "same school" idea is correct.> I bought five Chromis, and to make a long story short- 3 days later only one was left and the others all died with chunks taken out of their sides. <Uhh-Oh.> Seeing how Chromis are relatively cheap, I would like to give them one more chance. <Hmm...I'd re-think this.> Is there anything you could recommend me doing that would cut down on the chances of one Chromis becoming dominant? I tried to buy Chromis of all the same size but it did not work for me (though the dominant one was a little bit larger then the rest). <This would have been the only other strategy that I would have pursued.> Also the Chromis I have been seeing lately seem to look more white then blue/green. Is there a reason for this? <Could be a color variation (regional or otherwise)-or simply that you're dealing with some fish that are in poor health. Quarantine for these fishes (and all new additions, for that matter) is simply mandatory. They need frequent feedings of high-quality foods to be at their best and display good colors.> Thanks for the help. <Wish I had a better answer for you, but careful selection, quarantine and a healthy dose of luck seem to be the keys to success with these fish. Good luck! Regards, Scott F.>

Re: Blue/Green Chromis Blues (cont'd.)   6/21/07 OK, so if you don't advise getting Chromis for my tank I need to know what to replace them with. I was thinking a Tang but they might be a little too much for my 72 gallon. <Agreed> He is my what I was planning to put in my tank by order of purchase: 2 Ocellaris Clowns (in tank) 1 Neon Goby (in tank) 1 Flame Angel 1 Sixline Wrasse 1 Royal Gramma <A nice stocking list! You may want to reconsider the Sixline Wrasse, however, as they can get a bit nasty at times with other small fishes.> What do you think are some good replacements for the Chromis? I am trying for a peaceful community tank with lots of colorful fish. I also have 2 Cleaner Shrimp 3 Emerald Crabs and a variety of snails living in my tank. <Have you considered a group of Assessors? In particular, the Yellow Assessor, A. flavissimus is a great fish. You can keep them in pairs or small groups of 3-4 individuals. You should add them all at the same time. They are a bit pricy, but they are wonderful fish. Another fish that is colorful, peaceful and that you can keep in small groups would be the Canary Wrasse, Halichoeres chrysurus. Still another nice choice would be a Blenny of some sort- there are numerous species of varying colors and sizes-which can be really fun fishes to watch.> Thanks for the help. <Hope these recommendations are of use to you! Regards, Scott F.>

Re: Blue/Green Chromis Blues (cont'd.) Unfortunately, I am on a budget and do not have access to a large variety of fish as you may have. The Assessor and Canary Wrasse would not work for me. <I can appreciate that; the Assessors are not cheap.> I was thinking about a Kole tang as from what I have read they only grow to around 5 inches in captivity. Do you think this might work in my tank? <Of any of the Tang out there, this is the one that seems to attain the most manageable size, IMO. However, I personally am against keeping any Tang in an aquarium less than 5 feet in length, for the simple reason that these fish really need physical space to roam in.> Unfortunately (or fortunately) I do not have a large amount of algae growth at this time so I don't know if it would be happy in my tank. I would feed it Nori though. What do you think? <Kole Tangs belong to the genus Ctenochaetus, a specialized group of Tangs that are detritivorous in nature, and will also rasp diatoms from rock and hard substrates with their specialized mouthparts. Although the Nori would be nutritious for them, this is algae in a form that they may not be attracted to, nor adapted to eat. That doesn't mean that they won't eat it, just that it's not a "normal" food for them. Better for you to have lots of live rock, substrate, and rubble for them to forage among.> Also while searching through the fish I found a Dragon Goby that I liked and would do a good job of cleaning my sand. I was wondering, would he get along with my Neon Goby or the other members of my tank? <I'm not 100% which species the "Dragon Goby" is- there are several species that go by this common name. Would need the scientific name to be 100% certain which fish you're talking about. In general, however, most gobies seem to get along with each other, if sufficient space is provided. Assuming the "Dragon Goby" lives on or near the sand, the interactions with the Neon Goby, which tends to stay on rock surfaces. All this means is that, since the fish tend to occupy different niches, the interactions with each other would be limited, helping to diffuse any potential conflict. Gobies are always a great choice, IMO. Enjoy! Regards, Scott F.>

Possible Bossy Chromis? - 5/28/07 Hello All, <Hi Kyle, Brenda here> First off, your website is extremely helpful. <Thank you, glad you find it helpful.> I just have one problem. I have a 75 gallon FOWLR tank with various hermit crabs and snails. The only fish I have in the tank right now is a 2 and a half inch blue/green Chromis. Can I add 4 or 6 more Chromis and two ocellaris clownfish without worrying about the big Chromis bossing everyone around? He's had the whole tank to himself for 3 months! <Chromis are typically peaceful fish. You shouldn't have a problem with it harassing the other fish. You may run into problems keeping that many fish in your tank. It may be a bit crowded. Always quarantine your fish and only add one to two at a time to your system.> Your response would be much appreciated. Thank you, <You're welcome!> Kyle from Jersey <Good luck to you! Brenda>

Chromis viridis and Amphiprion ocellaris questions. New Marine Tank'¦. Compatibility and Stocking   7/6/06 Hello crew, <Hi Matt.>      Thanks again for this awesome resource. <And Thank you for the recognition, you are welcome.>   I've looked through the FAQ's <Sweet.> and still have a few questions. <That's why I'm here!> I have a 55 gallon tank with about 50 pounds of LR, skimmer, Emperor 400, and 2 MaxiJet 1200's.   <Well I would rather see a hang on refugium in place of the Emperor but it sounds good for the most part.> Currently the tank houses 1 coral banded shrimp, 3 peppermints, and a crew of a couple  dozen hermits and snails and varying species.  No fish yet. <Okay.> Ammonia and nitrite are 0, and nitrate <10. <All acceptable.>   I have two tank raised ocellaris clowns in  a 10 gallon and would like to move them into the bigger tank. <QT tank'¦awesome.> They are still juveniles, but seem to have paired up (although the female to be is pretty mean at feeding time). <Expected.> I would also like to add a school of five Chromis viridis to the bigger tank as well.  The clown tank will eventually serve as a quarantine, but the LFS will have to hold the Chromis for now.   Will these species mix without too many problems?   <It should though both species in question while relatively mild-mannered (well barring large female ocellaris which are anything but mild-mannered) are damsels'¦and still at times show aggression'¦but it should be okay.> Is this an acceptable bioload? <Yes.> Which species should I add first?   <I would like to see the Chromis go in first.> The clowns are currently doing fine in the smaller tank. <Cool.>   Sorry for the ridiculous amount of questions; <No worries.> I just want to make the transition as smooth for these fish as possible.  This setup will probably become a reef tank eventually and it seems that these fish would all be fairly reef safe. <Yes'¦> Thanks, <Anytime.> Matt <Adam J.> Chromis, Anthiine Compatibility - 05/05/06 Hi there WWM crew, <<Hello João >> I'm setting a 200 US gallon tank + 75 G sump and 27 G refugium (upgrading from a 55 G reef). <<Exciting times, eh?>> I'm planning on having 2 (mini) schools.  One of Chromis viridis (5 or 7) and one of Pseudanthias squamipinnis or bicolor (4 or 5). <<Let me recommend the lyretails (P. squamipinnis)...quite hardy and very beautiful>> I've been reading that, as time goes by, the Chromis start to attack and ultimately kill each other when defining their hierarchy and tend to reduce their number down to 1 or 2. <<Mmm, I've kept groups of three for years at a time...don't think five or seven in a tank your size would be an issue>> People don't seem to be able to keep a group for more than a few months to 1, 1-1/2 years.  Is that a fact? <<Not that I am aware...have seen tanks with five or more that fared quite well>> And what about their compatibility with the Anthias? <<Won't be a problem>> Looking forward to hearing your reply. Kind regards, João <<Cheers my friend, EricR>>

Chromis Query ... id, comp., sel.   4/8/06 Hi Y'all, <Chris> I'm just wondering if you could clarify any differences in suitability/temperament with Chromis or point me towards somewhere I can find more info - I have checked the WWM pages and FAQs already (& other sources) but can't seem to find the answers I seek. <... What little we have should be in the coverage, subFAQs coverage by the genus, family: http://wetwebmedia.com/marine/fishes/part2.htm Scroll down to the Damsels, genus...> My query is specifically around the differences between Blue-Green Chromis (C. viridis?), Blue Chromis (C. cyanea?) and the Green Chromis (with black spot at base of pectoral fin?) (C. atripectoralis?) <These are the most common species associated with these names... though there are often others> I have seen recently Chromis labeled as blue Chromis which looked (in my humble opinion) nicer than the blue/greens, it is difficult to tell from the picture on your Chromis page but the fishies that I saw had markings similar to blue devil damsels around the eye - small black splotch/band - does this fit with how blue Chromis are generally marked? <Mmm, if you mean mis-marked, labeled and/or appearing, yes> The colour of these fishies was consistent with the deeper blue (as on your page) than the blue/greens.  How do I differentiate between blue/greens and greens - is this the Pec fin black spot? <Not definitive... unfortunately. Some batches, source locations have this spot, others no.> Mainly my query is around the temperament of these fishies and any variances amongst variety - I am planning three of a single species for my new tank (a month or two before I start stocking yet - still working on the lists!) They will be sharing the tank with 2 Black & white Clowns, a couple of Banggai Cardinals & either a Flame Angel or a Coral Beauty (being tempted by the Coral B here) along with mainly SPS coral. On the basis of aesthetic value I am leaning towards the Blue Chromis (assuming you confirm that the fishies I saw labeled as such with the eye markings are indeed likely to be Blue Chromis) however behaviour and temperament (particularly as these are damsels!) are more important to me as I want all of my charges to co-exist as harmoniously as possible! On this basis is there much to choose between the blue, green/blue and green? <Viridis are the easiest going, most likely to mix with its own species, others... Cyanea next, Atripectoralis last... though all three of these Chromis are far to the left in terms of the spectrum of Pomacentrid aggressiveness. The short answer here is I'd go with the Blue-greens if this were a concern. Bob Fenner> Many thanks as ever   Chris

Chromis sp. 10/30/05 I like Chromis hanui but I want to know if they are peaceful?  <Generally much more sociable than their other damsel cousins.>  And are the legal to get? <Consult your local authorities, depends on your location. Adam J.> 

Midas Blenny biting its own tail, and Chromis Compatibility success, thanks to SteveA  10/6/05 Dear WWM Crew, firstly a big thank you for the previous advice (from Steve Allen) about dealing with a bullying blue-green chromis (Murdering Chromis - 6/5/05 - on Damsel Compatability FAQ's) - we weren't that keen/ able to just "get rid of it" as was his first suggestion, so we took a combination of his other two suggestions. We bought four more reasonably sized blue-green Chromises and quarantined then for 4 weeks. When their quarantine time was up, we removed the bully from the main tank into our very small treatment tank for a few days, and then introduced all of them into the main tank together at the same time. We now have a very happy shoal of Chromises, who seem to get on well together - thanks for the excellent advice. <Ahh, congratulations. Will send along to Steve> Sadly, of course, this is not our sole reason for contacting you. We bought a Midas Blenny about 5 weeks ago, and have quarantined him for 4 weeks. He has always remained a bit browner than he was in the shop display, but otherwise seemed pretty happy, and was taking a good amount of flake/ brine shrimp - have got some algae in the tank, and offered him some seaweed as well, but never seemed very interested. We put him in our main tank about 4 days ago, and he seems to have settled in alright, but last night we noticed him scratching against the rear wall of the tank, and also nipping at his own body (not the tailfin itself, but just in front). He is doing the same this morning as well. We have seen the same behaviour in a bicolour blenny we had, who subsequently died, at a time when all our other fish had ich. We thought we had dealt with the ich, by treating all the fish, leaving the tank fallow for 8 weeks, and quarantining new additions at least 4 weeks, and certainly none of the other fish (6 chromis) have any signs of ich at the moment. The blenny hasn't got any white spots (though by most accounts blennies often don't show spots when they have ich), and appears to be feeding well, though is still brownish-yellow rather than golden, <"Stress coloration"> so perhaps we shouldn't be too hasty, but this all seems very similar to our previous blenny's pre-terminal behaviour! We've taken him out into the quarantine tank (along with a large piece of live rock in which he was hiding - any suggestions for removing him from this?) <I would not. Will come out of its own accord>> . Tank parameters are: Main tank - ammonia 0, nitrite 0.025, nitrate 25, pH 8.2, SG 1.022, temp 26C ; Quarantine tank - ammonia 0, nitrite 0.01, nitrate 10, pH 8.2, SG 1.022, temp 26. I'm going to do a 20% water change in the quarantine tank today, and we'll need to get the nitrates down in the main tank, but we're worried about losing the blenny if we don't act early and aggressively enough, and so were thinking about treating him with copper. As always your expert advice would be greatly appreciated, Jim+Jo, Norfolk, UK <I would not treat this fish per se... and not with Copper unless there was obviously some cause. Very likely this "self-nipping" behavior is just "natural"... I would sub-tend the quarantine process with this fish, dip it in a pH-adjusted freshwater bath, and (risk) place/ing it in your main system. Bob Fenner>

Nascar Green Chromis  10/3/05 Dear WWM, I know you receive a lot of questions so I thank you in advance for taking mine. I am a new fish owner with a 37gal tall tank. The current inhabitants include two blue-yellow-tail damsels two green chromis and a juvenile golden wrasse. <... too much...> All the fish get along fine with each other  and I haven't seen any aggression problems. I have had the tank about three months and it has been stable for two (all the water parameters are fine). One of the green chromis (a resident of about a month now) has been acting strange ever since it was added. For the first two weeks it picked a place behind a large rock and stayed there not moving (except for it's fins) even during feeding times. I figured it was just stressed from the transition and just let him be. <Mmm, stressed and psychologically bullied...> One morning he was so still that I nudged him with my net to see if he was still alive. After three nudges he moved behind another rock. Lately though, he has had a new habit. He has taken up swimming around in a circle of about five inches in diameter, perpetually turning left. When I first saw this I was very excited and sprinkled a little food in the water as a reward for coming out from behind the rock. The other fish swarmed up and ate the food while the chromis never once broke stride in his circle. Have you ever seen anything like this? <Yes> His color looks good and the eyes don't appear cloudy at all. This afternoon I took my net and placed it in the middle of his race track and instead of moving around it he swam right in, looked confused for a moment, swam out and returned to his circle. If this is something you have seen before, is there anything I can do to help him or make him more comfortable? <Mmm, remove some of the other damsels, or place all in a larger world... at least sixty gallons> Also one quick question about my golden wrasse. I looked though your Wrasse FAQ's and I noticed that they generally do a good job of cleaning out crustaceans. Is this true for my particular species of wrasse or can I add things like shrimp etc? Thanks in advance, Justin <Is this a Halichoeres species? Bob Fenner> Fish compatibility 6/31/05 Hello Wet-Web Crew! Kudos to each of you for your continuing efforts. I thank you, and my fish thank you too!!  After reading up on the Blue-Green Chromis, I am wondering if you could advise if I should add these fish to my current set-up. I have a 90 gallon, 2 year old soft coral reef tank. It has about 90 lbs. of live rock. Presently, it is home to the following... 1 Royal Gramma, 2 Ocellaris Clowns, 2 Six-line wrasse, 1 Coral Beauty Angel and 1 Banggai Cardinal. Every one gets along swimmingly. (ha-ha -sorry)  I would like to add some of these Chromis, but how many? Based on the size of my tank, and population so far, what is your opinion?  If you think this is a poor option, I'm open to other stocking suggestions. I appreciate your input, and thank you sincerely, in advance.  Brenda  <Brenda, the Chromis' are a peaceful addition to your tank.  As far as stocking, I like to figure one cubic inch of fish per five gallons of water.  In your case that would be a total of 18 cubic inches of fish.  I like this method because actual body size is what you want to keep in mind, not length.  Of course you won't be able to come up with exact figures, but you should be relatively close.  With what you have in there now, an addition of three Chromis should pose no problems.  James (Salty Dog)>  

Stocking Questions (9-9-03) I have a 56 gallon Perfecto tank... roughly 20" high, 25" across, 15" deep.  My current inhabitants are as follows ( 1) 2" Maroon Clownfish (1) 3" Yellow Eyed Kole Tang (1) 11/2" Purple Pseudochromis (1) 2" Bicolor Pygmy Angel (3) Turbo Snails (2) Peppermint Shrimp Would it be ok to include 3-4 Blue Chromis in this tank?<The maroon clown and the tang will both need a bigger tank in the near future.  I would not add the Chromis until you get a bigger tank. Cody> Thanks for your advice!

New Stock - 11/20/03 I've now set up my new 150 gallon marine system- upgrade from a long run 75g- I've cycled and everything- ammonia 0, nitrite 0, nitrates are embarrassingly high 60+- but with a college bio/chem staff, we know its from our source water, so I'm not sure water changes would really help- what is a good water treatment product? <de-ionized filtered water ideally. Else Polyfilters and natural nitrate reduction from a deep sand bed> I was also wondering, with the following tank mates, would it be wiser to buy 3 or 5 blue-green Chromis? <they'd be much better off with 5 minimum to school> I'd rather do the healthiest thing for all 1 yellow tang 3"</DIV> 1 Hippo tang 4"</DIV> 1 Maroon Clown 3"</DIV> 1 3 stripe damsel  1"</DIV> 1 Yellow tail damsel 1"</DIV> 1 Blue damsel 1" </DIV> we may add a goby or two in January. I'm definitely going for a light bioload to help with nitrates.  I just bought over 2 liters of copepods/amphipods, and am going to let them populate in the 50 gallon 'fuge before trying any live food fishes- thanks, mike <skip the Chromis here Mike... your other fishes are too active and aggressive for the peaceful Chromis damsels. Best regards, Anthony>  

Cleaning substrate and fish compatibility Hi there. <Steve Allen tonight.> I have a 55 gallon fish only tank and about 100 pounds of live rock. I've been trying to figure out how to vacuum the substrate. Do you hook the hose on to your air pump or what? <No> I tried this but all that happened was it blew air into the water. <Not unexpected. There are a number of ways to vacuum substrate. The cheapest/simplest is with a gravel-cleaning siphon available at any pet store. Just vacuum with water changes. Personally, I use a Magnum 350 canister filter with the micron filter insert. The water goes back into the tank, so I can vacuum to my heart's content without fear of taking out too much water. There are also motorized gravel vacs you can buy that are hand-held and self-contained, but they seem rather wimpy and flimsy to me.> Currently I have 5 fish in my aquarium, 1 Scopas tang <Needs at least a 75G tank to thrive.> ,1 false Percula, 1 orange lined Chromis (he's lost his orange line and is turning brown) <Could be a sign of stress, malnutrition or disease.><<Or just this species developmental change. RMF>> a sixline wrasse and a dwarf hawkfish. I was wondering what else to put in with these guys. <Nothing at this point. You need to figure out what, if anything, is wrong with your Chromis. Any other fish that go in there should not be ones that can/will outgrow the tank.> I was planning on a mated pair of coral beauties <almost impossible to achieve in captivity> ,a valentini puffer <too big> another false Percula <you might be able to get it to pair up with the one you have. Read the clownfish FAQs about this. Do not add some other species of clown.> and a mimic eibli surgeon <I'm guessing you mean  Acanthurus  pyroferus, which grows way too big for your tank and will not get along with your Scopas.>  are these good choices? <Maybe the clown, and/or a single Coral Beauty.> thanks a lot. <Hope this helps.>

Chromis Hello! I would like a few Chromis for my 55g tank. I really like the Blackbar Chromis (Chromis retrofasciata). I read in a few places that this fish, like other Chromis, are peaceful and do well in groups. However, I've seen in a few other places that they're just as aggressive as other damselfish. Do you know one way or the other? << I'll say good fish. >> I would hate to spend so much time and effort to find these fish, only to have them not get along in my tank (with each other or with the other fish). Other inhabitants are 1 fairy wrasse, 1 lawnmower blenny, 1 clown goby, 1 chalk bass. << I think you will be fine, and in general I think Chromis are great tank mates. >> Thanks! Kari <<  Blundell  >>

Murdering Chromis (6/5/05) Dear WWM Crew, wondered if you had any ideas on dealing with a blue-green Chromis that has become a savage bully? <Get rid of it.> We didn't research things much when we made our first purchase of just 2 similar sized Chromises, but they seemed to get on alright despite not being in a larger shoal. Unfortunately we lost one of them to ich, but the other made a full recovery after treatment with copper. Worried that he might need some company, we purchased 4 more green Chromis from our LFS, who assured us that there shouldn't be any problems even though these were much smaller than our existing fish (c.1 inch vs. 2 inches). <Obviously, he was wrong in failing to consider that the remaining Chromis had established the entire tanks as his territory.> Right from the start he has been bullying his new tank mates, and there are now only 2 of the 4 left. We have separated them now, with the 2 smaller ones in a 60l quarantine tank, and the larger one on his own in the 240l main tank. The little ones seem much happier now, but we can't work out what to do in the long run. Should we try "feeding them up" and look to put them into the main tank when they're a bit bigger? or would it help to get 2 or 3 other larger damsels to try and "teach him to behave"? Any other ideas? Your advice would be, as ever, greatly appreciated, thanks, Jim+Jo, Norfolk, UK <Chromis, while relatively "peaceful" are still Damsels, and thus prone to territorial aggression. The simplest thing would be to catch him and give him back. The other thing you can try is to add a few new ones and significantly re-arrange the tank decor at the same time to confuse him so that he doesn't recognize his territory any more. He may then join the group as they will all be confused. This often works. The third option would be to catch him when it's time to put the others in and put him in the QT by himself for a few days so he forgets the other tank. Then you put him back in the main with the others after they've been there for a few days. Hopefully they all will then join up into one group. Hope this helps, Steve Allen.>

Green Chromis G'day to all. <cheers, mate... Anthony Calfo in your service> I have a 120 gal FOWLR that is 2 months old. current inhabitant is a 4 inch coronation grouper (Variola louti). I was thinking about adding 5 green Chromises. I know that when the trout gets bigger he will find the Chromises to be a nice snack but for the moment while he is small I think they would be okay. <I honestly disagree... many "groupers" will kill this passive fish out of territorial aggression. I'd give them 2-4 months to live and advise against it> the reason I am after the Chromises is I like the way they school up and there doesn't seem to be any other fish that will school up in an aquarium. <goodness gracious... there are many fishes that will do so. Heniochus, Footballers, hippo tangs... too many to list> if there is please let me know. will 5 Chromises add to much to the bio load of my tank, I think 5 would be a good number, do I add them all at the same time to preserve the schooling nature or is it best to add just a couple over a few weeks. <for schooling fishes... buy and add at the same time> tank is 120gal,wet/dry trickle filter, skimmer (producing a bit of gunk everyday) amonia-0, nitrite-0, nitrate-5, calcium-460, kh-12, ph-8.4. <very fine> 30 pounds l/r with coralline algae which is already really taking to my base rock. <more live rock if possible... a very good investment> some Caulerpa (put in 2 days ago). only other fish I am going to put in is a panther grouper (I know he will get large to). when the trout and grouper outgrow the tank I am able to release them to their natural area (I have regular access to the southern section of the great barrier reef, Australia.) thanks for your help, the website is a great resource. <please DO NOT release these fishes... besides being illegal, it is irresponsible my friend as your fishes in captivity can cultivate strains of disease that can decimate native fishes on the reef on release. Furthermore, if you buy fishes from a pet store or mail order them from places that hold fishes from all over the world, your "native" fish might be exposed to an "exotic" disease in holding tanks that you cannot see. To release this into the wild can wreak havoc. It is a very serious concern my friend. Please never release ANY captive held fishes and obey the local laws if not the natural law. Best regards>

Blue Reef Chromis Dear Bob & clones: <<I hope I'm not a clone... JasonC here.>> I just received 3 blue reef Chromis, which I specified to be no longer than 1" because of my miniscule inhabitants of my main tank. My problem is this: one fish is about 1" the other two are really big, one really huge (comparatively speaking). <<Even if you had gotten them in the size you wanted, surely they would never stay that size.>> Bob told me to add fish small than present inhabitants of my tank. They consist of a teeny dwarf angel, about 1-1/2", a royal Gramma (about 2 inches a clown about 1". I called flying fish, where I bought them (I had specified no more than 1", and he told me they would replace my pygmy angel if he died in battle. The fact is we have become attached to Bob and don't want he done in by a large blue Chromis. <<Chromis aren't typically that aggressive, and you might be surprised by the resolve of an angel who has been in the tank longer to hold its own.>> How serious is this problem? <<I would give it a shot and see... could be no problem at all.>> Flying fish suggested going to local fish stores and doing a trade, but the fact is local fish store usually have green Chromis, real small. What would you do if you were me? <<I'd give it a shot, if there is aggression from the larger Chromis, yank them and haul them down to the LFS and negotiate a trade.>> I don't know if I can even do a trade, but these guys would wipe out the present inhabitants. <<I'm not convinced.>> I am worried about my pygmy blue angel, because the largest one is bigger and the same color I don't want WWII in my tank. <<It may never happen.>> The guy from Flying Fish says he will replace my pygmy angel, but as I said earlier, we like him and don't want him destroyed. I didn't know reef fish came so big and hearty. I thought they were smaller. <<They come in all shapes and sizes.>> What is your fix on this situation? <<I wouldn't be that concerned.>> I live in the SF, CA area, and the fish stores don't have much and they are not very willing to order. Thanks for your help, Connie Cavan <<Cheers, J -->>

Green Chromis I have 2 saltwater tanks, one with 3 large (2-2 1/2") green Chromis and the other has 5 small (1") Chromis. In your experience, will there be any problems with combining them in 1 tank? Will they school or stay separate? <I have concern that the larger ones will actually bully the smaller ones to death. I would not recommend the mix> Thanks, Rich
<best regards, Anthony>

Become a Sponsor Features:
Daily FAQs FW Daily FAQs SW Pix of the Day FW Pix of the Day New On WWM
Helpful Links Hobbyist Forum Calendars Admin Index Cover Images
Featured Sponsors: