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FAQs on Pangasiid Cats Mainly the Iridescent/ID "Shark"... Systems

Related Articles: Pangasiid Catfishes

Related FAQs: Pangasiid Catfishes 1Pangasiid Catfishes 2, & FAQs on: Pangasiid Catfishes Identification, Pangasiid Catfishes Behavior, Pangasiid Catfishes Compatibility, Pangasiid Catfishes Stocking/Selection, Pangasiid Catfishes Feeding, Pangasiid Catfishes Disease/Health, Pangasiid Catfishes Reproduction, Related Catfish FAQs:  Identification, Behavior, Compatibility, Selection, Systems, Feeding, Disease, ReproductionMinnow Sharks 1,


ID Sharks and saltwater?     2/27/20
Hello! I, like many others, purchased some ID sharks a few years back not being aware of the size they would reach; my mistake.
<Yeah; up to some 1.3 m in length. Have seen some four footers in public aquariums. The group at the Wilhelma Aq. in Stuttgart my fave ex.>
Now I am doing the best I can to accommodate them and keep them healthy and happy. They are
currently 9in at the largest (of 4) in a 100gal tank, and I have plans to get a 300gal very soon.
<And beyond this?>
My issue is that I've been running into a lot of conflicting information about the salinity they should be kept in...many sources say brackish, another senior hobbyist told me as adults they would need salt, but here you say strictly fresh. Please help me keep my babies healthy, I made the mistake of purchasing them, they shouldn't have to suffer for it. Thank you, Mareena.
<Good to check other references. Here's FishBase:
This is an all-freshwater species of some tolerance in terms of pH and hardness... The keywords here in terms of practical husbandry are OVER sized system, filtration, circulation, aeration... And UNDER feeding. AND good sized weekly water changes (like half). No need to add salt/s. Bob Fenner>
Re: ID Sharks and saltwater?     2/27/20

Thank you so much! Knowing I don't have to step up a marine tank actually opens up my current options for getting a larger tank than even the 300. I really appreciate your help!
<Certainly welcome. Do remember to feed sparingly, keep temperatures in the low to middling seventies F to forestall the time when you'll need to move these monsters! BobF>
ID Sharks and saltwater? /Neale      2/27/20

Hello! I, like many others, purchased some ID sharks a few years back not being aware of the size they would reach; my mistake.
<Understood. Iridescent Shark Catfish do get large, and while 1.2 m or bigger lengths are possible in good conditions, typical aquarium specimens, even in public aquaria, are more likely to reach around 70 to 90 cm. So while still very large fish, they are, just about, manageable in really, really big tanks. In some ways the bigger problem>
Now I am doing the best I can to accommodate them and keep them healthy and happy. They are currently 9in at the largest (of 4) in a 100gal tank, and I have plans to get a 300gal very soon.
<Sounds good.>
My issue is that I've been running into a lot of conflicting information about the salinity they should be kept in...many sources say brackish, another senior hobbyist told me as adults they would need salt, but here you say strictly fresh.
<The true Iridescent Shark, Pangasianodon hypophthalmus, is absolutely a freshwater fish. There is a species, Pangasius krempfi, that appears to have a brackish or marine stage in its life cycle. But otherwise, no, they don't need salt.>
Please help me keep my babies healthy, I made the mistake of purchasing them, they shouldn't have to suffer for it. Thank you, Mareena.
<Hope this helps, and best of luck. Neale.>
ID Sharks and saltwater? Neale, re ID     2/27/20

<<Does strike me that there may be confusion here with Colombian Shark Catfish, Ariopsis seemanni. These are estuarine catfish that migrate back and forth between the sea and large rivers. While not ridiculously big (20-30 cm is typical) they are highly gregarious which means a big aquarium is necessary to keep a group of at least 3 and ideally 5+ specimens.
Cheers, Neale.>><Mmm, B>
Re: ID Sharks and saltwater?     2/27/20

Mareena; per Neale's query... are these cats ariids or pangasiids? The first ARE marine as they grow. BobF
Re: ID Sharks and saltwater?     2/28/20

As far as I've been able to determine, they are true Pangasianodon hypophthalmus, three regular and one albino. I feed them sinking carnivore pellets, baby shrimp, and bloodworms on a rotation.
<Well, the two species are quite distinct... Had me going on reading Neale's concern, as you stated you'd had these fish for years... Usually very fast (VERY) growers. Cheers, BobF>
Re: ID Sharks and saltwater?     2/28/20

Ah, of course. The oldest two are 3 1/2 years now, the younger two are 3. I would say the longest is around 9-10 inches at my best guess. Their only tankmates are two 6in angelfish currently.
<They will eventually ingest the angels if kept together. B>

Iridescent shark seizures  6/21/10
Hi There...
I searched your site, couldn't find an answer to my question. My 4 year old iridescent shark has been having seizures the last several days. At first I thought it was the lighting, so I've kept it off, no fix. The only thing I've changed in his environment lately is I started feeding his tank mates a different type of flakes. Can you tell me, is there anything I can do to help him stop having seizures? Should I go back to the old food?
Thanks in advance for your reply...
<It's unlikely to be seizures as such, and more a fright reaction. Unless your aquarium measures thousands of gallons, your aquarium is too small. Seriously. I'm not kidding. Pangasius hypophthalmus ARE NOT suitable for
home aquaria. They get to about 120 cm/4 feet long within a year or two, and they live in groups, and they migrate up and down rivers. Under home aquarium conditions they almost never adapt, and most specimens die
prematurely for one reason or another. At the very least, they end up damaging their eyes by throwing themselves into the glass walls of the tank. Stunting is common, and despite the common myth, doesn't mean the fish has "grown to the size of its tank" but instead means the fish has been chronically stressed for a long time. If yours is less than, say, 75 cm/30 inches, your catfish is stunted, and that means it is probably being kept badly. In short, you need to make sure the tank is very, very large, has an extremely strong filter [8-10 times turnover per hour] and that there are no aggressive tankmates likely to spook them. Do not EVER keep this species singly; it is just as social as a Neon tetra or Tiger barb, and will be just as stressed if kept alone. I honestly wish I could say something more helpful, but I really can't. These fish DON'T adapt to home aquaria, and usually end up damaging themselves precisely in the way you're describing. I doubt the change in food was the trigger, but possibly the tankmates are behaving differently and that's alarmed your catfish. Who knows. Without being told something about the size of the aquarium or its tankmates, I can't really say anything more detailed. I know I'm being super-negative here, but these are fish that shouldn't be in the aquarium trade, and there's really no excuse for shops to stock them or people to
buy them. Every aquarium book ever written has something like "don't buy this fish" written down under the Pangasius catfish name! Cheers, Neale.>

Stress or not happy with food? Pangasiid incomp., FW stkg. period/hex tanks   1/24/10
I just revamped my tropical tank.
New (plastic) plants, new decorations and reintroduced all the fish at the same time in an effort to reduce stress. I have provided as many hiding places as possible for my fish.
<Sounds promising.>
It's a 55-gallon hex tank,
<Do be aware these are generally not good choices, and in terms of stocking a hexagonal aquarium of 55 gallons will only hold the same number of fish as, say, a 30 gallon rectangular one. Why? Because of surface are to volume ratio. A hexagonal tank this size has the same volume but lower surface area than a 55 gallon rectangular one. Less oxygen can dissolve into the water, and less CO2 can diffuse out. I don't recommend hexagonal, spherical or any other shaped aquarium other than a low, long rectangle. Sometimes, old school is the best!>
I keep the water at 78 degrees and have a Penguin filter that I keep two cartridges in at all times. (Done to increase the amount of carbon to help keep the water clear.)
<Actually, carbon only removes dissolved organic chemicals, the stuff that makes water tinted yellow over time. It has zero benefit in terms of removing solid particles such as silt that make water cloudy. Indeed, it's rather better to take out the carbon and replace with filter floss if silty water is a problem. In most freshwater tanks, carbon is redundant.
Manufacturers sell the stuff happily, given how massively overpriced it is, but me, I prefer to save my pennies.>
The water is still a little cloudy from the water change I did yesterday, but it's clearing up as expected.
In the tank we have a Plecostomus (about four to five inches in length - the giant one we traded in because I didn't need both of them in the tank),
<Has no place in a tank this size/shape.>
two small Cory catfish and an incandescent shark.
<Corydoras should be in groups of 5+ specimens of each species, and an Iridescent Shark (Pangasius hypophthalmus) has absolutely no place in this aquarium. Given its maximum length is well over 120 cm (more than 4 feet)
I'd strongly argue this fish shouldn't even be in the fish trade. Sure, most specimens in aquaria don't get that big. That's because they usually end up dead first. But the lucky survivors still get to a good 60 cm (2 feet) or more in length, and public aquaria really are fed up with taking unwanted specimens. On top of that, this is a schooling, riverine species that needs to be kept in groups in a spacious aquarium. In small tanks -- and yours is TINY by the standards of the species -- this fish ends up throwing itself against the glass, damaging its eyes. Many, MANY specimens are blind precisely because of this (and needless to say, with a beaten up head and cloudy eyes, pretty ugly looking as well).>
Obviously those are our cleaner fish.
<NO such beast. If you imagine any fish, ANY FISH, will make an aquarium cleaner, it's time to do some reading. Think about it. Adding fish adds the amount of food you need to add. That fish defecates, meaning there's more silt. That fish excretes ammonia, so there's more work for the biological filter. That ammonia becomes nitrite and then nitrate, feeding algae. So the tank becomes more algae-ridden. In every possible way, adding fish makes tanks dirtier. End of story.>
The rest of the tank holds two Mickey Mouse platys, two sunset platys, one female Betta, one Dalmatian molly and five tetras.
<Finally, some fish that make sense. I'd argue the Molly is better in a community where adding marine salt mix is an option, but I'll let that pass for now. These are small fish that would be happy in a tank your size and shape.>
So far it seems like everyone gets along,
<So far...>
though I admit my female Betta is a little ticked off since she used to rule the roost (it used to just be her, the Corys and the Pleco). But she's doing pretty well, she just sort of chases the others around checking them out, but I haven't noticed any aggressive behavior on her part.
I noticed today when I fed them, that the platys would take the food in their mouths and then immediately spit it back out. It's tropical flakes, it's what the people at the pet store said to feed them. (Which, from what I've seen on your site isn't the right thing to be feeding them.)
<Indeed. While flakes are fine up to a point, these are herbivores, and their diet should include as a staple Spirulina flake, plus things liked cooked peas and Sushi Nori. It won't kill them giving them flake, but offer them the green foods too. Usually, tetras ignore Spirulina flake, but catfish happily eat it. Indeed, Corydoras eat a lot of algae in the wild.>
Are they spitting it out because they don't like the food, or is it because they are still stressed after the water change I did yesterday?
<Unlikely because they're "unhappy" about the water change, but check water quality. If you have added a bunch of fish all at once, or were too aggressive when it came to cleaning the biological media in a mature filter, you could have higher than zero ammonia and nitrite levels. This would explain their odd behaviour. Also check the flake isn't stale. Open pots last about 6-8 weeks in a dry climate before they lose their savour.
Don't buy huge pots expecting them to last all year. If you must, decant small portions from a big tub into a small pot, and store the big tub in an airtight container somewhere cool and dry (just like you'd do with any dried human food, like cereal). Next up, offer a variety. Fish get as fed up with the same thing every day as you would. Once a week offer live brine shrimps or wet-frozen bloodworms. Finely chopped (raw) fish fillet or seafood is good too. Don't add anything from warm blooded animals though:
no meat, no chicken, and no dairy. While fish will often eat these things, with a very few exceptions, in the long term such foods cause problems.
Shredded beef heart and hard boiled egg yolk are the two main exceptions. On the other hand, all sorts of plants foods can be tried, including softened vegetables like courgette, spinach, lettuce and cucumber.>
Should I worry - or are they actually getting some of the food despite some of it coming back out?
<If it is still occurring within a couple days, yes, be concerned.
Certainly check water quality now. Platies need hard, basic water (10+ degrees dH, pH 7.5-8) with 0 ammonia and 0 nitrite. They actually prefer slightly cool water, around 22-25 C. Do review the needs of fish prior to purchase, and choose species with similar requirements.>
They all swim all over the tank (except for the molly, she hangs out near the top, and she's pregnant, so I'm not surprised by this behavior)
<Could be unhappy; review "the Shimmies" and be aware of the VERY specific needs Mollies have for long term health.
Most folks keep 'em wrong, and so end up with sick Mollies.>
- so I think they are all healthy. I'd just like to head off any potential problems to keep them from getting sick in the future. I'm an amateur, so I don't know everything, but I'm trying to do what's best for the fish ... I hate to see animals suffer, be they marine or not!
<Quite right! I applaud your philosophy here.>
Thanks for the help!
<Happy to be of help. Good luck, Neale.>
Re: Stress or not happy with food?
Neale, thanks for the advice.
Wow, I thought I was doing better ... but I guess I still have a lot to learn!!
<As do we all.>
I would prefer a rectangular tank, but I inherited the 55-gallon hex and you know, when we're talking a free setup, you take what you can get.
<Indeed. But it's also true that if you do inherit a tank like this, you understand the limitations, and choose fish accordingly.>
I would like to clarify one thing - the shark is an incandescent shark catfish. It's not the iridescent shark you referred to. :)
<Exactly the same fish. Pangasius hypophthalmus. Google the Latin name, and take a look. Indeed, Wikipedia has a photo of this fish alongside the common name you used.
I'm not a big fan of common names for precisely this problem. With a Latin name, you know where you stand. With common names, who knows what kind of fish is being sold!>
I'm not that inhumane!
<Most folks aren't inhumane deliberately... but the nature of the fishkeeping hobby is that the variety of species on sale far exceeds the abilities of most aquarists to keep them properly.>
But, as you so aptly pointed out, the catfish and Pleco aren't necessary...
Even so, thanks for the help. I'll cook up some peas with dinner and offer those to my patties and see if that helps.
<Hope this works. Cheers, Neale.>
Re: Stress or not happy with food?
Stupid petstore guy! ARGH :) I'm sure you hear that a lot.
<Unfortunately, yes. What can I say? I try my best, but there's just one of me, and fifteen million bozos out there. Cheers, Neale.>

Iridescent Shark, beh., sys.  10/27/09
Hi, was just wondering if you ever heard of a fish slapping its jaws together as if it was eating something but has nothing in its mouth.
<Nope, not seen this. Might be some sort of threat display? Or could be "gulping" water, a sign they aren't getting enough oxygen.>
This is not constant but happens probably once or twice an hour. Since they started doing this, they have been swimming really slow and kind of hovering about an inch or two off the ground. The fish are iridescent sharks,
<Pangasius hypophthalmus, I presume?>
one is about six to seven inches long and the other is about five to six inches long.
<Ah, well, these fish almost never do well in aquaria. You do realise how big they get? Easily 60 cm/24 inches, often 90 cm/36 inches and in the wild more than 120 cm/48 inches. These are food fish, and cannot be kept in home aquaria.>
They are in a 125 gallon tank,
<Too small.>
nitrate between 0 and 20, nitrite is at 0, hardness between 75 and 150, chlorine is 0, alkalinity is 120-180, and ph is about 7.2. temp is 78-79.
The eyes are clear on both of them, I can not see any skin problems to include the fins. The larger of the two damaged his nose when he was introduced to the new tank about a month ago as he was really quick to spook.
<All too common. These are riverine fish used to swimming freely. They almost never adapt properly to home aquaria.>
He is no longer so easy to spook and his nose looks like it healed well with no infection visible to the eye.
<Well that's good to hear.>
The fish seem to eat well only when we are a distance from the tank.
They never used to do that, it really didn't matter if I was standing right in front of it before.
<The bigger they get, the more space they need. In this teeny-tiny tank (by their standards) they're feeling horribly cramped and stressed.>
They also stopped taking food from the surface, they strictly eat from the bottom now. Also was wondering what the max amount of fish you would recommend for this tank as I keep reading how the groups are best around 3 but I'm sure you will tell me the tank is currently to small for 3 even at their current size.
Any opinions would be appreciated
<Time to buy a much bigger tank, or else do what 99.9% of the people who buy these fish end up doing, and that's finding a new home for them at a zoo or public aquarium. These fish simply shouldn't be in the trade, and I can't imagine why anyone would buy them. All the aquarium books state very clearly DO NOT BUY THIS FISH and yet people still do. Pangasius hypophthalmus are food fish, and no more suited to home aquaria than farmed food fish species like Atlantic Salmon, Channel Catfish, Common Carp, or Sea Bass. Cheers, Neale.>

Bottom feeder suggestions for tanks (Oh no, Pangasianodon; run, run!) 2/11/09 Hello WWM crew, <Hi,> In my 30 gallon hexagon, I have 2 Kribensis cichlids. I'd like to add maybe 2-3 fish that are middle to top level dwellers. <With Kribs? Most anything that stays at the top should work. Danios are the obvious option, but lack of swimming space may limit things. The problem here is that hexagon tanks are notoriously poor in terms of fish stocking capacity. They have a terrible surface area to volume ratio, meaning little oxygen diffuses in compared to the standard broad but shallow rectangle. You've also got less swimming space, so while Danios would be great in a 30 gal. rectangle, they're less happy in a deep but narrow hexagon. All things considered, I'd consider the smaller Danios like Zebras and Pearls, or alternatively White Cloud Mountain Minnows, in both cases assuming the temperature is no higher than 25 C (77 F), since neither likes super-hot water. (Nor do the Kribs, by the way.) Alternatively, you could go for surface swimmers that don't move about much, for example Silver Hatchets or even a single African Butterflyfish.> Can you recommend a bottom dweller that's tough enough to handle the cichlids but efficient in eating uneaten food? No matter how careful I am with trying not to overfeed, my cichlids are not interested in eating much. <Then feed less! Even if you add fish, that uneaten food gets turned into ammonia, and then into nitrite, and ultimately nitrate. Ammonia and nitrite are immediate killers, but your filter should remove them just fine. Nitrate is an insidious killer, and if you skip water changes for a couple of weeks, nitrate levels can easily get high enough to kill cichlids. Seriously, cichlids (including "hardy" Kribs) are sensitive to levels above 20 mg/l, so handling uneaten food isn't the goal, keeping excess food out is. Personally, I'd avoid catfish with Kribs: Kribs are pretty vicious when defending their territories, and can damage things like Corydoras (biting out there eyes!). Again, you have the problem of a poor surface to volume ratio, meaning that there's less "bottom" in this tank than would be the case with a 30 gal. rectangular tank. As should be apparent, while hexagonal tanks might look nifty, they're actually pretty seriously compromised in terms of keeping fish. My best suggestion would be to go with some of the snails, like Nerites or Tylomelania, that don't breed much/at all in aquaria, or even shrimps like Cherry Shrimps. These will all be ignored by the Kribs, and will help eat algae, uneaten food, etc., up to a point at least.> My 30 long tank has 20 assorted platys, swordtails and mollies. I'd like to add a few Corydoras in this tank but I'm already overcrowded. I use a Penguin 350 filter and no salt in this tank so would this be okay? <I'd not add Corydoras to this system. I like the fact you've given these fish space, and by choosing livebearers, you reserve the option to add marine salt mix at, say, 3 grammes per litre, if the Mollies start getting sick (as they often do in busy freshwater tanks). If you really must add something, consider making the water slightly brackish and getting something like Knight Gobies. Not only are these attractive fish, they're very efficient predators that will keep the numbers of livebearer fry down!> I have 4 iridescent sharks, 2 parrot cichlids, 3 black skirt tetras, 1 kisser and 1 Danio in my 55 gallon tank. Can I add a small Pleco, which one? <You are MASSIVELY overstocked already. Do you have any idea how big those Iridescent Shark Catfish will get? Do take a look at the Fishbase page for Pangasianodon hypophthalmus, here: http://www.fishbase.org/Summary/SpeciesSummary.php?id=14154 http://www.fishbase.org/Photos/ThumbnailsSummary.php?ID=14154 See the fishes these chaps are holding in the photos? That's your catfish. While 130 cm (4 foot) specimens are not common in aquaria (!) they can and will reach about half that size, and astonishingly quickly. I simply cannot stress this strongly enough: these aren't fish for the home aquarium, and the majority of specimens end up having to be killed or given away to zoos (who don't really want them). For what it's worth, most any common Plec species, e.g., Pterygoplichthys multiradiatus, would be fine in a 55 gallon tank, assuming strong filtration and regular water changes. Do understand that the common Plecs of the hobby, Pterygoplichthys spp., get to at least 45 cm (18 inches) within 3-4 years, and are incredibly messy vegetarians. They need filters rated at not less than 6 times the volume of the tank per hour (i.e., at least 330 gallons per hour in your case) and big (50%) water changes every week or so. Otherwise your aquarium will end up looking extremely murky.> Thank in advance for your help. Audra <Happy to help. Neale.>
Re: Bottom feeder suggestions for tanks (Oh no, Pangasianodon; run, run!) 2/11/09
Hi Neale, <Audra,> I agree with you about the 30 hexagon, I only bought it because it looked good. It took me a long time to decide what to put in it and my Kribs are already spawning after being in the tank for a week. I'll consider the Zebra Danios. <Cool.> In the 30 long, my mollies have done well without salt, so I won't be venturing into brackish water for them at this time. <Fine. But I'd still recommend keeping them with tankmates that at least allow you the option of using a therapeutic dose of marine salt mix, even if you don't actually go fully brackish. Hence, salt-tolerant livebearers and killifish good, soft water catfish and tetras bad.> Thanks for the pictures on the sharks. I nearly had a coronary (kidding). But I've known about their size for a while now. Two of my iridescent sharks are about 10 yrs old now and 7 in. long, the other two about 5 yrs old and 4 in. long. <Hmm... still quite small. May well be one of the other Pangasiid species. None make great aquarium fish, though, even "tiddlers" like yours. Nervous, skittish animals prone to damaging their eyes, in my experience.> If I had done my research years ago, I would never have bought them, but they are my favorites. <They are certainly nice fish. Just difficult to house. Yours have done extremely well to have lived such a long time. By NO means the usual thing.> I plan to move the tetras, kisser and Danio out once the cichlids get bigger, so my sharks will have more room. My dream tank is a 110 gallon for them but this will have to wait. <Indeed.> I do 3-20% water changes a week on each tank so this helps keep things in order. I love Corys but I don't have an existing set-up where they could fit in. <Tell me about. My poor Peppered Catfish get attacked or nipped or chased wherever I seem to put them.> Thanks for all the suggestions Neale. Audra <Cheers, Neale.>
Re: Tank mates prob. (Oh no, not Pangasius hypophthalmus!)  12/25/08
Hello dear Neale, I hope you will be fine there. Neale I want your help that I have 2 iridescent sharks and 2 giant Gouramis in 90 gallon right now. <Hello Ali. I'd be a lot more "fine" if my time wasn't being wasted. I don't mind offering advice, but when it's ignored, and you come back for more advice, that isn't really very good for my ego! Let me be 100% crystal clear on this. You have NO BUSINESS at all keeping Iridescent Shark catfish (Pangasius hypophthalmus). Firstly, they are SCHOOLING fish. Two specimens is not a school; you need groups of 5 or more. Next, they get to 130 cm (over 4 feet) long and can weigh over 40 kilos (100 lb.). There is NO WAY you have the space to keep such large fish. Most specimens damage themselves in aquaria because they cannot handle things like glass walls. They become blind for example, because they bump their eyes into things. Giant Gouramis (Osphronemus spp.) are not much smaller, typically around 60 cm in length and a weight of 9 kg (about 20 lb.). Individuals can be very territorial towards others of their species, and I suspect the two specimens you have will not get along once mature.> But Neale I am very interested to keep 2 black ghost knife and 2 parrot fish with them. <Get rid of the Pangasius hypophthalmus first. Then worry about maintaining good water quality for six months. Understand Apteronotus albifrons will die at the first sniff of ammonia and nitrite, and will not tolerate pH changes. So keep testing water quality and chemistry in your tank, and if it is ABSOLUTELY perfect every single week from here to June, then maybe think about a Knifefish. Otherwise, leave them alone!> Can they live happy and calm with each other in one 90gallon tank? <No.> Thank you, Ali <Ali, please understand the best I can do is to prevent you making mistakes. In this case, I've said repeatedly that Pangasius hypophthalmus is NOT a fish you (or ANYONE ELSE) should keep as a pet. It is a food fish, not an aquarium fish! Merry Christmas, Neale.>
Re: Tank mates prob. (Oh no, not Pangasius hypophthalmus!)  12/25/08
Hello dear Neale, I am sorry I didn't mean to hurt you; I always listen to your advice and did whatever you said. <Ah, that's the best Christmas present!> I have returned the iridescent shark and giant Gourami back to the pet store. <Extremely WISE decision.> Now I am doing what you have said about maintaining the water condition. Please suggest me any fish that you think is best, ill introduce them when water condition become normal. My goldfish are fine now they are doing well. <I would start with a group of either Bronze or Peppered Corydoras (Corydoras aeneus or Corydoras paleatus). Get six or more specimens of each species. By all means keep both! These catfish work EXTREMELY well with Goldfish, and enjoy the same water temperature. Corydoras will do just fine at the 22-25 C that Goldfish enjoy. They stay relatively small, are completely peaceful, and being air-breathers, will not suffer in summer if the water gets too hot. Another great fish to keep with Goldfish is the Weather Loach (Misgurnis anguillicaudatus). It gets to about 20 cm, is great fun, and works well in groups of 3-4 specimens. Giant Danios (Devario aequipinnatus) are fun with Goldfish, but they are boisterous and may terrorise fancy Goldfish; they work best with standard (non-fantail) varieties such as Common Goldfish, Comets and Shubunkins. Perhaps surprisingly, the Variatus Platy (Xiphophorus variatus) can work well with Goldfish; it's a herbivore, so will do well on similar foods. Couple other choices include White Cloud Mountain minnows (Tanichthys albonubes) and the Green Barb (Barbus semifasciolatus).> Thank you, Merry Christmas, Ali <Likewise, and a happy new year to you, too! Cheers, Neale.>

Iridescent Shark in BW?     2/11/07 Hi there, first off I have gotten tons of excellent information from your site. Thank you for that. <Glad to hear it.  Pufferpunk here with you tonight.> My question is two part, I have 2 iridescent sharks and a Pleco, in a 175 (I know they get big and when they get bigger, I'll be moving 1 to another tank).  They are only 3" and 3 1/2" long right now. <It is highly unlikely you will ever be able to house even 1 iridescent shark properly.  Here's a pic of an adult: http://smg.photobucket.com/albums/v345/Pufferpunk/Other%20Fish/?action=view¤t=iridescentsharks.jpg > I would like to know the possibility of keeping them in a brackish tank setup? <No, these are strictly FW fish.> I would like to get a puffer that gets large but it would require brackish conditions. <The larger BW puffer (green spotted puffer, Tetraodon nigroviridis), actually will eventually need quite a lot of salt, even marine conditions as adult.  There are many FW puffers, some that can get quite large, like the Fahaka puffer but are much too aggressive for tank mates.> If that isn't possible for these fish, are they compatible to keep with an Oscar?  These 2 attacked some the four mollies that were in the tank when I brought them home. <They will eat whatever fish they can fit into their mouth.  If the Oscar is the same size or larger, they should be compatible.  You need to consider what you will do with these fish when they get larger.  It's almost impossible to find homes for them once they are large.  ~PP>   Thank you for all the info, Terry

ID shark woe I have been doing some reading and it seems I should not have an id shark in a 33 gal tank. He is about 7 inches and I love him but should I give him away to someone with a larger tank? boo hoo? If I give him back to the fish store won't they just sell him to the next ill-informed hobbyist?  <I would move this fish... to a larger system... it will be "unhappy", too likely to jump out, harm itself dashing into the side of your 33> They told me my tank was fine when I suggested it may be too small. I think he may also have fin rot. What should I do about that? Melafix or Maracyn II. <Best to move it to a larger, clean system... allow it to self-heal, quick!> Anywho if you could set me up with a good list for a freshwater community tank which already houses 1 Pleco, some java fern and some corkscrew Val I would greatly appreciate it as the local fish store people seem to know squat ( they also told me 6 comets would be fine with my id shark, a school of neon tetra and two black Kuhlis in a 33 gal tank). <What? Goldfish in with tropicals? No... do take a look through the survey articles on freshwater posted on WetWebMedia.com> It is frustrating when the people I turn to give bad advice. You are now my knight in shining armor. <Not too shiny> I e-mailed you yesterday with some info if you recall but will do so again. 33 gal tank DynaFlo 3 filter 3 way cartridge filter temp mid 70's <Be chatting, Bob Fenner>

A black iridescent shark question I have a black iridescent shark approximately 6 inches long. I noticed yesterday that it looked like he had a festering sore right behind his left-sided fin; now today it looks like an actual hole. I called the local pet store, but they weren't sure and would do some checking - any ideas what it is and what to do for it???  I did a water check and everything is right on where it should be.  He's in a 55-gal tank with another iridescent black shark, platys, Dragonfish, Dojos, clown loaches, and has been since May of this year.  Thanks in advance. <Hi Cheryl, Can you give us the actual readings on your water? Ammonia, nitrite, nitrate and pH. Also, what is your water change schedule? Your sharks problem may have to do with high nitrates. That's a lot of "soon to be large" fish in a 55 gallon. As adults the sharks will reach over four feet! You'll need to plan for there long term care. The clown loaches will hit eight inches or more. With this many growing fish it's common to have your nitrates spike quickly. Long term high nitrates can cause skin problems.   Also, I'm not sure what you mean by "Dragonfish", common names being what they are. Do you have a link to a picture? Don>

Iridescent shark We have an iridescent shark that has out grown our 55 gallon tank. It was 3-4 inches long when we got it, and is now 14-15 inches long.  It kept running into the sides and was not able to turn around with out getting skittish.  Had made several jumps to the top and scraped chunks out of the skin.  One night it actually jumped out of the tank onto the floor.   We bought a 125 and that was very hard on the shark to move it.  The fins got caught in the net, but everything has healed.  
<<Better by far to "scoop out" such fishes w/ large (doubled) plastic bags... you can get used from a fish store or use thick trash bags... Do dump out most of the water before lifting! RMF>>
Our problem is, since we have moved the shark, it has not eaten.  It has been about a month now.  We have fed tetra flake food, sinking pellet food, which is what it ate all of the time, krill, Tubifex worms.  Temp is about 75, changed the water last night and the nitrate was a little high, but still not eating.  Have platys and Cory cats, which was in the other tank with it also. Any suggestions  -  HELP  we have put a lot of money and effort into this shark and do not want anything to happen to it. < Try raising the water temp to 80 degrees F. They come from fast moving waters so make sure the filter is adequate for the tank and pumping at least 400 gallons per hour. Make sure that the water has zero ammonia and nitrites and that the nitrates stay below 25 ppm. I think I would add an airstone to increase the aeration of the water too. Try keeping the light off for awhile and let him get use to the new tank. You fish may have sustained some internal injuries during the move. If the above suggestions don't improve things in about a week then I would recommend treating the tank with Metronidazole. This will be expensive in a big tank but I don't think I would risk moving him again.-Chuck> Thanks SSimpson

I was just wondering, can I keep an Iridescent shark( Pangasius hypophthalmus) in a pond of about 2 feet deep?  9/1/05 <That is not really a question of depth, but of the temperature in your pond, and the filtration. You would need consistent temperatures above 75 F, and a good strong filtration. This species is also a bit sensitive to Ick and I would be concerned in a pond where it will be difficult to examine. Good Luck, Oliver >

Monster Tank I just purchased a 36 gallon tank after I had a very bad week with my 5 gallon tank. I had an iridescent shark & 4 goldfish. All the goldfish died one day at a time. The shark barely survived. We had to do an emergency 1/2 water change, change the filter, clean the bio wheel & he still appeared dead. He was literally vertical head up, tail down, I finally got him back with holding him horizontal with the net. A few days later, he is alive & well, although very lonely. I stick tested the water & there were extremely high levels of nitrate (before the water change). Now that I bought the 36 gallon corner unit fish tank I need help deciding what the best filtration system would be. As a kid I had a 20 gallon tank with an UG filter along with a regular filter. That seem to work great, but with such a large tank I'm not sure what would be best. Now they have those canister filters, the filters that hang inside the tank, the UG filters & probably more. We purchased an UG filtration & a Tetra Whisper Power Filter 40. The instructions actually suggest the Tetra Whisper Power Filter 40i which sits inside the tank (better for corner units). So before I start taking these back to the store & purchasing new ones, I was hoping for some good advise. Should I use 2 filters or just a canister filter or just one that sits inside the aquarium? I am hoping to transfer our survivor to the new tank & use the 5 gallon tank for 1 or 2 goldfish for my daughter. I also hope to add another shark & some other fresh water fish to the new tank. Should I also put live plants in the new tank? I have never experienced that either. Please help me have a healthy aquarium. Thank you, Amanda <Amanda, you have a monster in your tank. You need to return the shark. An Iridescent will grow to over four feet! Please see here: http://www.planetcatfish.com/catelog/pangasii/pangasiu/172_f.php Even a single Goldfish is to many for a five gallon. If it has a filter and heater a Betta and a few Corys would work. Without a heater try about 5 White Clouds. Never clean a Bio Wheel. It's function is to grow a bacterial colony that removes ammonia from your water. It takes weeks to recover once lost. I hate UGFs, I wouldn't put it in. If you already did, I suggest you remove it. So, you need to go to the pet store. Take back the shark. No way around that unless you want to flood your basement for him. Pick up a test kit for ammonia, nitrite and nitrate with a new filter. Many fine brands/styles on the market. I like the Marineland Power Filters with the Bio Wheel. Get one that will pump around 225 to 275 gallon per hour. Do not bring home any fish. Get the filter running and the temp around 78. Throw in a small raw shrimp. First ammonia, and later nitrite will spike and crash. When they stay at zero and nitrates are on the rise you are "cycled" and can start to slowly stock your tanks. No water changes

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