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FAQs on the Rainbowfishes Foods/Feeding/Nutrition

Related Articles: Rainbowfishes Fishes at the rainbow's end;  An introduction to the Atheriniformes, the rainbowfish and silversides by Neale Monks

Related FAQs:  Rainbowfishes 1, Rainbowfishes 2, & FAQs on: Rainbow Identification, Rainbow Behavior, Rainbow Compatibility, Rainbow Selection, Rainbow Systems, Rainbow Disease, Rainbow Reproduction,


New rainbow fish won't eat; env.        9/25/19
Hi I noticed as soon as I got my new rainbow fish they weren't eating. They take food in and spit out 90% of it. Doesn't matter what it is.
<Assuming the food is palatable and appropriate, "spitting out" food is usually a symptom of some sort of stress. Might be stress from moving, might be water chemistry or quality, might even be existing tankmates. But once fish are happy, they will eat whatever appropriate food is offered. So your real job here is to see what's bothering your fish.>
I messaged the place I got them asking what the supplier fed them and mentioned the issue and they just ignored me.
I have a 130 liter tank, the new fish are 5 dwarf neons, 2 very small boesemanni, 1 Kutubu rainbow. All pretty young juveniles.
<Rainbowfish are sociable, and in small groups can behave oddly. While your mixed group might well work for now, adult males of the two bigger species might become aggressive, or conversely, in the absence of their own kind, Rainbows kept in ones or twos can become nervous or skittish.>
Other than that I have 2 Siamese algae eaters and 2 long armed shrimp and 2 mystery snails.
<Long-armed Shrimp (Macrobrachium spp.) are not trustworthy with fish, so be careful here! Don't have a lot of hope for the Apple Snails either, which tend to do poorly in tanks with anything likely to peck at them.
Observe for signs of damage or stress.>
I've tried all 3 types of Fluval flakes and pellets, New life spectrum pellets and flakes, blood worms and Repashy's food. They just spit everything and of they keep any down its not much. Iv tried dosing
Praziquantel incase they have gill flukes, now Im on a course of Avitrol plus tabd incase its internal parasites. I feed their food soaked in garlic guard with Metroplex and agar agar. I have no idea what's going on.. are these fish doomed or have I overlooked something?
<See above. What's the water chemistry? Rainbowfish tend to prefer neutral to slightly basic water chemistry, around 10-15 degrees dH, pH 7-8 being typical. Some variation among species and even collecting localities, but for the most part avoid acidic conditions. They dislike very warm water, and do appreciate moderate water flow and lots of oxygen. They do need open swimming space though, and your tank will certainly be too small for adults of the two larger species.>
<Hope this helps, Neale.>
Re: New rainbow fish won't eat     9/26/19

Hi Neale thanks for your reply. The tank is stable at 25 degrees. They seem very keen on food and swim together. Theres no obvious signs of stress apart from spitting food out. When i got them they had tiny bit of white on some of their lips, ill see if it got worse tomorrow when i turn light on (the Levamisole is light sensitive).
<I would treat as per Columnaris, just in case it is Mouth Fungus.
Columnaris is quite common with Rainbowfish, and being a more aggressive bacterium, can quickly become life threatening.>
The long arm shrimp haven't harassed or killed anything.
I had a minor ammonia spike around 0.5-1 from an Oto dying (of starvation, they wouldn't eat).
<Otocinclus essentially only eat green algae and aufwuchs, and while some specimens will take algae wafers, it's hit and miss. Many do indeed starve, or are at least dangerous starved by the time they're brought home, and between that and any underlying infections, simply never recover.>
And maybe the tank wasn't cycled due to too much plants.
<Not how this works. If the plants are using up ammonia "in real time", that's perfectly fine and doesn't mean the filter won't develop.>
Unsure, the ammonia just never went up, its heavily planted with a lot of Anubias.
<Unlikely Anubias grow fast enough to absorb ammonia in real time. Conversely, being epiphytes, their roots are exposed to the water and harbour plenty of useful bacteria across their surface area.>
I moved the 2 mystery snails and all the ramshorn snails into a 10 liter container with a filter and heater for the meds because I think the Praziquantel was killing off Ramshorns.
<Can do.>
Ph is pretty low, kh also low. It comes out of the tap between 6.8-7. Kh it comes out is about 3.In my tank the kh drops to 0 and the ph was around 6.4-6.6I have to add minerals and kh buffer to keep it up. Could that be the cause? Ill do a test in a sec to see what they are now.
<Would certainly be something I'd be concerned with. Blue Rainbowfish really needs around 15 degrees dH, pH 7.5. They do not live long in soft, acid water. Boesemani Rainbows are essentially identical in requirements. The old Rift Valley salt mix should do well. Use at about one-quarter to one-half the recommended dose, i.e.,
Per 10-20 gallons/40-80 litres:
1 teaspoon baking soda (sodium bicarbonate)
1 tablespoon Epsom salt (magnesium sulfate)
1 teaspoon marine salt mix (sodium chloride + trace elements).
Mix enough for your tank in a jug of warm water, but add in stages, across several days ideally, so that the fish are not exposed to sudden changes in pH and hardness. Thereafter, add appropriate amounts for each bucket of new water.>
The SAE is huge so I think the adult rainbows should be fine because they dont get as big as SAE right?
<Should be fine, assuming a true Siamese Algae Eater and not one of the more temperamental lookalikes such as the Flying Fox. Cheers, Neale.>
Re: New rainbow fish won't eat     9/26/19

Hi Neale thanks for your reply. This is video of the fish
<Nothing came through or was linked.>
Would Seachem equilibrium fix the hardness issue?
<No. Seachem Equilibrium raises General Hardness, which will help your Rainbowfish to some degree, but doesn't affect the Carbonate Hardness, so won't raise the pH much, if at all.>
I also have seachem kh. And benibachi mineral balls
<No idea what these are! But looking online they seem to be some sort of mineral that supposedly dissolves slowly in the tank, like a seashell or limestone rock would do. While theoretically fine, after these are coated with algae and bacteria, the minerals are isolated from the water. So their
effectiveness, especially if not cleaned frequently, is likely to be low.>
Im going to check the water parameters now
<The product you want (from Seachem, at least) is Alkaline Buffer. It even has a Boesemani Rainbowfish on the bottle!
While this should work very well, it's a lot more expensive than the home-brew mixture I described earlier. Cheers, Neale.>
Re: New rainbow fish won't eat      9/26/19

Hi again Neale. I tested the water:
Temp: 25
Ph: 6- 6.2
<Much, much too low for Rainbowfish.>
Ammonia: <0.25
Nitrite: 0
Nitrate: 1
<Very skeptical of this! Nitrate is almost never less than 5-10 mg/l in typical aquaria unless your tap water has no nitrate (unlikely) and the tank is so lightly stocked the plants absorb all the nitrate produced by the biological filter.>
Phosphate: 1
Kh: 0? Took the original drop to change
<That's why your pH is so low.>
Gh: 0? On first drop it was yellowy then added 22 more and it stayed yellow
<Again, you really don't want zero general hardness for Rainbows. Your aim is around 5-15 degrees GH, 5-10 degrees KH, and a pH around 7.5. Sodium carbonate provides KH, while Epsom salt is good for general hardness. Alternatively, you can use a commercial product like the Alkaline Buffer mentioned earlier. Should raise KH safely, and provided that is sufficiently high, you can largely ignore the GH. Cheers, Neale.>
Re: New rainbow fish won't eat      9/26/19

Hi Again Neale thanks for your reply
Its just because I already have Seachem Alkalinity
<For carbonate hardness.>
and Seachem Equilibrium.
<For general hardness.>
Could I attach them to a doser?
<Not sure I see the point.>
I have a Jecod dp 5 doser. How much at one time should I aim to raise the kh and gh? 1 degree or 3?
<Easiest approach would be to make a bucket of water to the right KH and GH, making a note of how much of each product required. Change 10% of the water in the tank today. Repeat the next day, and so on. By doing a series of small steps, the fish will adapt just fine, and you won't need to faff about with the exact numbers.>
Thats the video
<Nice tank, if a bit small for the species concerned, Your Anubias look better than mine -- sadly my Panaque scrapes the leaves so they look like a Swiss Cheese Plant! Cheers, Neale.>
Re: New rainbow fish won't eat      9/26/19

Hi again Neale in reply to the water parameters, tap water has 0 nitrate, 0 ammonia and 0 nitrite. and the ph ranges from 6.5-7.One time it was 6.5 and week later it was near 7.
<Lack of buffering evident here.>
Im using seachem matrix and marine pure in a AquaOne 800 nautilus. Maybe that's reducing nitrate?
<Not if it's doing its job, it isn't. Biological filters, especially canisters, generate nitrate. Some aquarists refer to them as "nitrate factories" which is a bit harsh, but not entirely wrong.>
The nitrate was dosed (using continuum) to 5ppm on the 14th and today on the 26th it is about 1 or less. Its pretty close to yellow. I dont know why all the minerals are so low. I think its the tap water it has 3kh and 0gh as well.
<Sounds like it.>
The plants eat up the kh.
<No, they don't. Some plants do biogenic decalcification, such as Egeria and Vallisneria, when kept in the hard water they like. But these are fast growing species able to 'tap into' that carbonate hardness as their CO2 source for photosynthesis. Your Anubias, even if they were able to do this (and I don't think they can) grow so glacially slowly that the rate at which they consume CO2 (or carbonate hardness) would be trivial.>
I also have a lot of drift wood so maybe that's lowering the ph, unsure. Or could be kh in general?
<Both. Wood creates acidic chemicals; absence of buffering, such as KH, will mean the pH drops between water changes. If your water has a low KH, the acids could react with that small amount of KH, as a neutralisation reaction, and very quickly you'd have no KH left.>
<Cheers, Neale.>
Re: New rainbow fish won't eat       9/28/19

Thanks Neale
I followed the instructions on the containers as I hadn't received your message yet. Ill test the water tomorrow. What kh and gh should I be aiming for?
<See previous messages, please. They're up on WWM Daily FAQ as of now:
Search for "Re: New rainbow fish won't eat" and your messages are all there.>
I ordered test strips incase something weird is going on with the test kit gh. I think the thing hanging on the fishes mouth is not fungus but a parasite of some sort. As I saw one fall out and hang by a longer strand then fall off a fish which was kind of weird and surprising. Maybe the medication is killing them off?
I noticed the fish are ravenous and eating more and keeping it down it seems. They are liking the Dainichi mini pellets. Though if it is a parasite Im unsure which med is the one that's killing them, the Prazi or the Levamisole? Hmm
<Hmm indeed. Keep observing, and focus on the water chemistry for now.
Cheers, Neale.>
Re: New rainbow fish won't eat       9/28/19

Hi Neale when feeding my fish today they ate way more than usual and are very hungry.
The neons still have white thing hanging on their lips though. Any ideas what it is or how to get rid of it?
<I would assume Columnaris unless there were evidence to the contrary.>
Thanks. One of the neon males gills are flared and redder than the rest.
The neons gill are kinda red, the Kutubu and boesemanni look fine though. I think it may be a female Kutubu.
Wonder what could cause the red gills?
<As mentioned earlier, improper water chemistry is a stress factor, so focus on that first, and see what happens.>
Should i do another 3 day lights off and medicate with more Levamisole?
Should I do a water change and gravel vac?
<One or more water changes before a second course of medications is always a good idea.>
I still have Praziquantel in the water from last dose and Levamisole but the Levamisole has been light exposed so probably not in water much now? Or should I be doing a Methylene blue dip or something? Not sure
<Please don't randomly medicate while water chemistry is being dealt with.
Get water chemistry right, then observe your fish, and then medicate if a problem is positively identified. Cheers, Neale.>
re: New rainbow fish won't eat       9/28/19

Hi Neale just wanted to mention the male neon rainbow that has it the worse seems to breath harder and open and close his mouth a little.
<Could easily be acidosis.>

Im considering adding some aquarium salt to the tank at low amounts, would that be a good idea?
<Not especially, no.>
Not sure how much is ok for the plants
<Anubias handle salt well, especially at trivial doses as used for medicating against Whitespot, and they will even adapt to slightly brackish water just fine. But salt isn't a replacement for proper general and
carbonate hardness (except if brackish water fish are being kept) so focus on those parameters instead. Cheers, Neale.>
re: New rainbow fish won't eat       9/28/19

Hi again Neale Thanks for your reply. Ok I will continue to buffer water to ideal number. Is there anything I can add to the filter which will keep it buffered so i dont have to keep adding chemicals?
<Yes, but it's more work that adding tiny amounts of Rift Valley salt mix or equivalent to each bucket of new water. If you put small amounts of crushed coral into the filter these will slowly dissolve, but at an
unpredictable rate, and they'd also need to be cleaned every week or two otherwise they'd be so covered with much their effectiveness would decline significantly.>
<Cheers, Neale.>
re: New rainbow fish won't eat       9/28/19

Hi Neale thanks for your reply
The ph is 6.8 today.
<Getting better. Small steps towards the optimal pH, which is around 7.5 to 8, is the way to go. Don't rush!>
I was thinking of adding some crushed coral in the filter to boost kh and ph without having to mess with chemicals all the time is that a good idea?
<No, for reasons outlined previously. In the short term, what you get is an unpredictable rise in pH and hardness. Can I tell you how much crushed coral you need? Or how quickly the hardness and pH will rise? Or where the hardness and pH will level off? Nope. Crushed coral is best reserved for use in tanks where high pH and hardness is happening anyway, such as a Malawi, brackish or even a marine tank. In a standard freshwater tank, it's essentially the same as swinging a sledgehammer blindly around your head in the hope it'll hit a very small nail somewhere in the neighbourhood.>
Should I use half a cup or a whole cup?
<See above.>
Ok I didn't add salt but I added 1 cap of seachem ParaGaurd.
<Fair enough.>
I will add another cap later then to full dose. Is that a good idea?
<I always recommend to use the full dose for the full duration as stated by the manufacturer UNLESS you have specific reasons not to. Half-doses may be ineffective, and can also lead to antibiotic resistance, which we really don't need in our hobby.>
I read its good to help treat infection and parasites
<Yep, one of the better general purpose cures.
By no means 100% effective against everything, but a good choice when dealing with mild infections (i.e., the fish are active and feeding happily) to help their immune system do the job. Cheers, Neale.>
re: New rainbow fish won't eat      9/29/19

Hi again Neale thanks for your reply.
The fish are going great and eating so much more now.
<Good to hear.>
Though the fungus on the 5 neons lips is still there. Any ideas how to treat it?
<As per Columnaris would be my recommendation.>
I just wasn't sure if ParaGaurd is safe for my shrimp and snails since it has malachite green.
<It is unlikely to be safe. Remove some/all of these to another container for the interim, and return to the tank after the course of treatment is over and several water changes have been carried out.>
I suppose I will add the full dose then of the ParaGaurd. That is a good point.
<Glad you think so!>
What about a cuttle bone? Im guessing dolomite or limestone is off the table then as well lol.
<Cuttlebone no better or worse than limestone. Unpredictable and eventually covered with dirt or algae.>
Perhaps ultimate aquacare has a liquid ph/kh buffer i could add to my Jecod doser.
What's your thoughts on these two? What's better? They also have a gh one
<This latter would be my preferred choice given the warning the other one has about use in fish-only tanks, which is more or less the case with a tank planted with mostly slow-growing species like Anubias. But I'm struggling to see what the difference is, since they both seem to contain potassium carbonate! Cheers, Neale.>
re: New rainbow fish won't eat      9/29/19

Hi again Neale thanks for your reply. I didn't add the full dose of ParaGaurd. I will add carbon to remove it now.
<Good move.>
What medication should I use for the fungus that's safe for my shrimp?
<There aren't any that I'm aware of. And to stress again, Columnaris, so-called Mouth Fungus, is a bacterial infection.>
<Cheers, Neale.>
re: New rainbow fish won't eat      9/29/19

Hi again Neale Thanks for your reply. So what meds are there that would treat it?
<I use a product called eSHa 2000. Another good choice, probably better in fact, is Seachem KanaPlex.>
Or would it go on its own?
<Sadly not, if this is Columnaris. This disease is notorious in suddenly killing whatever fish is infected, because it can progress really rapidly.>
<Welcome. Neale.>
re: New rainbow fish won't eat      9/29/19

Hi again Neale,
What's your thoughts on me trying TriSulfa or seachem Sulfaplex for the mouth fungus?
<Yes, Sulfaplex should work. Do visit the Seachem website when researching their products; it is very clear.
Used as instructed, as an antibiotic is should not cause problems to snails or shrimps, but as ever proceed with caution.>
Is that a good idea? Do you think its safe for the large shrimp? I could move them to be with the snails tho
<Cheers, Neale.>
re: New rainbow fish won't eat      9/29/19

Hi again Neale thanks for your reply. I ordered Sulfaplex it should arrive by Thursday. Should I try to swab treat it or just treat in water?
<Use as directed:
Unless you happen to be a vet or microbiologist, disregarding the manufacturer's instructions is never a good idea!>
Do I add to food?
<No point if the fish are not eating it, but if they are eating, feeding moderately will do no harm.>
Should I stop feeding medicated food now?
<Again, see the instructions linked above.>
The food was medicated with Levamisole, low dose Praziquantel (was in same product) and Metroplex + garlic guard.
<Deworming medications should be fine with antibiotics, but I wouldn't be using them unless you have good reason to, just in case. Cheers, Neale.>
Re: New rainbow fish won't eat      10/8/19

Hi again Neale thanks for your reply.
The prawns started eating the snails so I rehomed them. The rainbows mouths are improving and eating much better now but I noticed a lesion of some sort on 1 side of a male neon. Maybe he got nipped by a prawn? Unsure I got a video what's your thoughts on what it could be? Do they look healthy aside from the mouth fungus stuff?
<Hard to say. Male Rainbowfish will fight, and sometimes fish bash into lighting fixtures and the like when alarmed. Certainly a marauding Macrobrachium might be suspect. I'd treat as per Finrot or Mouth Fungus (ideally, one med that does both) and see what happens. Cheers, Neale.>

Millennium Rainbows Emaciated      7/13/14
Hello WWM! I’m wondering if you can help me out on an issue I’ve been witnessing with my Millennium Rainbow's I bought five months ago… One male, one female. Both were roughly two inches at purchase and filled out well and healthy looking, but now, five months later, as all my other varieties of Rainbow’s have grown fat and happy, those two have grown thin, sickly in appearance, and drastically lost color. None of the other fish display similar issues and the Millennium’s are not harassed by the other fish. Here is what I currently keep in my 55 gallon tank:
2 millennium rainbows (one male, one female)
2 turquoise rainbows (one male, one female)
3 yellow turquoise (one male, two female)
2 Australian splendida rainbows (one male, one female)
1 Synodontis lace catfish
Temp stays at 74 degrees F
Nitrates/Ammonia all ok (regular 30%-50% water changes weekly, as Rainbows prefer)
PH 7.0
From start-up, I used 4 Neon Blue Dwarf Gouramis and my Synodontis Lace (whom so desperately needed out of the 30 gallon) to cycle to the tank. After 3 weeks, I then added all of my above fish, except for the Yellow Rainbows. Then, after another 2 weeks, I removed the Gouramis (took them back to the fish store) and picked up the three Yellow Rainbows. During this time, I only fed Tetra Color flake food to the rainbows and all of them ate it without issue. It was when I brought home the Yellow Rainbows, that I began to feed frozen bloodworms. I believe I may have ‘over-did it’ with the bloodworms, as I fed them a cube and a half total per day, spaced out over three feedings. My ex, (whom was a manager for a big name fish store in the area for 23 years) scolded me for feeding them so much, and said I needed to focus more on flake food, and cut back to feeding one or two times a day. So I did…
But then I noticed that the Millennium Rainbows had no interest in the flake food, (which became breakfast) and would hold out until I fed the 1/2 cube of bloodworms (which became dinner). They simply shot the flake food right back out of their mouths, and then began to not even ’taste’ it at all, practically turning their noses up at it, so to speak. I was told by everyone that they would “come around and start eating the flake food again”, but even after 4 weeks of this routine, they did not. It felt all wrong not feeding them like I was before. It was during this time that I noticed they began getting thinner.
Then, at 9 weeks, I thought that some of my rainbows had developed 'mouth rot’, a white fluffy fungus on their lips. It seemingly bounced from one fish to another. I first treated with a cheap mainstream fungus cure, that turned my water a horrendous radioactive green. I used active carbon after the appropriate time, cleared the tank and waited. The white ’stuff’ continued to appear randomly on my fish. I was told by the fish store that my tank was in ‘dire straights’ and needed Seachem Sulfathiazole. I followed the directions. Nothing changed. Later, I discovered via the web, that rainbows can damage their lips by bumping into things, etc. and I took the chance that that was the problem and stopped dosing my tanks. Lo’ and behold, within 2 weeks, the problem never worsened and eventually disappeared.
At this point, my tank was 12 weeks old. All fish were doing very well, but my Millennium’s were drastically thinner, their color gradually fading, especially in the male. They were the slowest in the tank now, hovering in the corner together, never moving except at feeding time, and their poop began to turn clear. I decided to go back to feeding bloodworms multiple times a day, as I was before, to see if they fattened back up... But to no avail. I even added beef heart and brine shrimp on occasion, and still offered flake food for the other fish, and while they ate whatever I put in the water, the two Millenniums STILL only ate bloodworms.
Now, I’m at the five month mark, and all the rainbows have grown exponentially, but the two Millenniums look like ‘death warmed over’. Their activity HAS increased, as they both now swim with rest of the school since I went back to feeding them bloodworms more often, but the once golden female is now a horrid brownish yellow and the once brilliant red male is a silvery, faded pink. He doesn’t even flare his fins like he used to, instead opting to keep them laid tight to his body, making him look almost identical to the female. Their poop now at least has color to it again, instead of being clear-ish, yet both of them are an entire inch smaller than all the other rainbows and even more shockingly thin. The males of my rainbows are all beginning to have the pronounced ‘big body/little face’ appearance, yet the male Millennium is still straight and narrow, like a female.
I’m at a loss. Is this common? Do Millenniums have a history of being picky eaters? What could be causing their emaciated appearance?
I just added another male Millennium today, which is what prompted my question, because the newcomer is a brilliant red and fat and happy… He makes my other two look even more like they have one fin in the grave. And so far, he eats the flake food when offered. None of my other rainbows show the slightest signs of illness. Where did I go wrong with those two? Could the medications from before have been a factor? Or is it an issue with their eating habits?
And am I over-feeding at 3 times per day, with 1 and 1/2 cubes of frozen food total per day, even though my tank stays clean and balanced? I’ll take any suggestions or thoughts on the matter at this point. Thanks so very much for your time.
<Greetings. My gut feeling here is Mycobacteriosis, which is a problem with Rainbowfish. Not a common one, but a persistent one. The big issue Mycobacteria is that they're effectively untreatable. You can do quite a lot to prevent them causing sickness, but once they're there, your fish are pretty much dead men walking. Mycobacteria are potentially contagious too, though it's hard to quantify this because environment seems to trigger Mycobacteria infections that are latent (i.e., there, but harmless) in aquaria generally, so it's difficult to say if the second fish was infected by the first or merely succumbed to poor environmental conditions later than the first fish. Make sense? Worms are also a risk, as with any tropical fish, but compared to Mycobacteria they're a lot easier to treat using a proprietary antihelminthic medication (such as PraziPro) and you might do this anyway, so you can tick off this possible problem. Anyway, Since your aquarium is relatively young, evaluating and disregarding environmental factors causing ill health will be the first step. Rainbowfish are fairly adaptable, but for the most part they appreciate neutral water that isn't too hard or too soft, so review water chemistry. Most don't like extremely of temperature either. Likewise, water circulation should be brisk but neither sluggish nor turbulent, and oxygenation should be high (which is one reason not to overstock their tank or keep it too warm). Diet is always a factor to review; good quality flake is ideal, but as you seem to realise, bloodworms are kind of like Chicken MacNuggets but for fish -- readily eaten, but not sufficient by themselves. On the other hand, underfeeding Rainbowfish is easily done; they seem to have large appetites and perhaps limited ability to store nutrients, so frequent small meals are better than one or two big meals. It's also possible you got a bad batch of bloodworms; indeed, some aquarists I know refuse to use them at all, citing the conditions they're reared in as proof enough of their inappropriateness as aquarium fish food. I will direct you now to the www.rainbowfish.info website, among whose members is Adrian Tappin, one of the foremost experts on this group of fish. They may be able to offer you a second opinion. Cheers, Neale.>

Rainbows choosing not to eat?   6/22/11
Hi all.
I have some questions relating to the dwarf neon rainbowfish, Melanotaenia praecox. I purchased four of these fish (two males, two females) and put them into a 29 gallon tank that has been set up for about a month and is fully cycled (see water quality and decoration details below). Existing tank inhabitants are six Corydoras aeneus.
These rainbowfish have been in the tanks since Sunday afternoon, and it is now Tuesday evening. During that time, I have tried feeding them two different varieties of flake food (Aqueon tropical flakes and Tetra Color Tropical Flakes), both of which are fresh, not stale. I have also tried feeding them freeze dried bloodworms (Tetra brand), which I just purchased and opened tonight. The fish don't seem to notice the flakes or bloodworms on the surface, but as they sink to their level they go grab them readily enough, getting entire pieces into their mouths and then closing their mouths, sometimes for as long as five seconds. But then they invariably spit them out. The flakes/worms look about the same size when spit out as they did when they went into their mouths, so I'm not sure if they have swallowed anything at all since I've gotten them. Can you think of any explanation? Eventually the foods gets to the aquarium floor where the Corys attack it, so I'm sure they aren't getting anything later when I'm not watching. I called the fish store and asked what they've been feeding this fish, initially thinking they were just finicky, and they told me flake food and bloodworms, so I'm really perplexed by this behavior. I guess I maybe should have asked whether those bloodworms were live, frozen or freeze dried, and more details about the flake food (they said it was their store brand), but it still seems strange they won't eat two brands of fresh flake food or freeze dried bloodworms.
<Indeed, but sometimes fish are picky. Wet-frozen bloodworms are usually very good at tempting new fish to eat. Live brine shrimp and daphnia are also very good, but watch they don't get sucked into the filter -- if you want, switch off filters for a few minutes while they're feeding.>
Otherwise, these rainbows appear perfectly fine. They are beautiful with great coloration, no signs of disease, and they swim around the tank normally. They were shy at first and spent a lot of time hiding in the plants, but I am starting to see them more often in the open area now so they appear to have mostly overcome that.
I have Googled other sites and read many of your FAQs, but can't seem to find anyone with this problem. Most describe them as greedy eaters of flake food. Any advice would be appreciated, as I would really hate to lose these beautiful fish due to inexplicable starvation.
Tank & Water Quality Data:
Ammonia: 0 ppm
Nitrites: 0 ppm
Ph: 8.0
General Hardness: 12 degrees hardness
Carbonate Hardness: 15 degrees hardness
Temperature: 74-75 degrees F
Substrate: Small size rounded aquarium gravel
Decorations: Many artificial silk plants, one real piece of Mopani wood
Filtration: Emperor 280 filter with Biowheel, and the normal filter cartridge (floss/carbon). Also weekly 25-33% water changes are done.
Thanks for your help!
<All sounds fine. Fish will go off their food when stressed, so keep an open mind. Otherwise don't feed for a few days, and then offer some food.
Cheers, Neale.>

Madagascar Rainbows Won't Eat Dear Friend <Good morning to you my friend> I have an urgent question - I have recently bought some Madagascar Rainbows - they looked well at the store but since then they have little interest in what I am feeding them. I read that they would take flakes. After they did not, I tried dried bloodworms and later frozen bloodworms. These do not seem to interest them. Three of them just died, no doubt by starvation. <You might try feeding them small live foods. Small fishes (if you're sure they're disease free) or live worms such as bloodworms. Sometimes even small earthworms will entice finicky eaters.> Kindly help. Thank You. Faris <You're welcome! Ronni>

Bloodworms for Rainbows  8/25/06 Hello, <<Hi, April. Glad to have you back! Tom here again.>> I need some expert advice that I have not been able to get at the pet store and haven't found searching the internet.  Can you help? <<You know I'll try.>> Here it is: I have 7 threadfin Rainbowfish (Iriatherina werneri).  Three males and 4 females.   <<Very nice choice, April.>> I had planned on getting more, but the LFS was "closing them out". The males were added first and hid and shook for 4 days before coming out. The females were just added 5 days ago and you should have seen the males change.  They were parading around the females and even changing colors.   Very pretty and impressive. <<Boys are definitely show-offs regardless of the species. :)>> Okay, the question.  I bought frozen bloodworms as this is what they were getting at the store along with flakes.  The package has separated cubes to defrost and feed.  The problem is this is way too much.  I just today put a few in the tank and they seemed to like them.   I read that this species has small throats and food has to be small.  Do I need to cut the worms smaller (yuck)?   <<The worms will be soft enough for the fish to chew what they can of them. I wouldn't be concerned about this aspect.>> How long can I keep the rest of the defrosted worms in the fridge?   <<Personally, April, I wouldn't store these for more than a few days at most.>> I did plan to feed the bloodworms once a week.   <<A couple of times a week won't hurt at all. They're a good supplemental food source.>> With people food I don't keep in the fridge longer than 4 days.  So I wonder if I should give a few more in 4 days then toss the rest? <<Wasteful as it seems, this strikes me as the best course of action, April.>>   I also thought it a good idea to feed the worms the day prior to or the day of cleaning/water change to get rid of the uneaten worms. <<An excellent plan in my opinion.>>    I read about the foods that Rainbowfish like in general, but due the threadfins smaller size, do you know of better food choices? <<Not better but you might consider frozen brine shrimp, as well. Small enough, I should say, and also a good supplement. The downside is that it brings us right back to the "problem" with over-supply. One thought would be to see if it's possible to snap one of the cubes in half with a sharp knife, preferably without shooting a chunk of frozen bloodworms through the kitchen window. :) The future alternative would be to go with the freeze-dried variety, the smallest container you can find. Freeze-dried foods lose none of their original nutritional value and would eliminate the waste. As for purchasing small containers of food, I recommend this because the food goes stale after a time. I don't hold on to any of mine for more than three months before pitching it out and buying new stuff for my guys.>> P.S.  I want to thank you again for your previous help when I lost the first fish to ICH.  I waited, tested and researched before purchasing these threadfin Rainbowfish.  I really was ready to just give up with the whole aquarium deal.  But thanks to your help and encouragement, I have a nice healthy tank with beautiful fish.  I couldn't have done it without you. <<If I were having a bad day up until now, that's over with, April. I can't think of a nicer compliment and I pass that on for all of us here at WWM. Thank you.>>   Tom, I changed my mind about the "blue Rainbowfish" (8/6/06) since they didn't know or want to know what the scientific name was.  Got me worrying about how big they would really get and how healthy they were. <<Well done. Actually, it's, legitimately, Melanotaenia praecox. Provided there's been no "tampering", these would have been a good acquisition but, between you and me, I like the Threadfins better. My best to you and the whole "crew", April. Tom>>  

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