Help identifying this fish

I have two of these long fish with thin vertical black bands….they are almost 3” long now. They are slightly aggressive, but haven’t hurt any other fish yet. They do aggressively go after the frozen bloodworms I feed my other fish (Rainbows and Angelfish mostly), and they have eaten a snail I had.

What are they? I am worried they are going to keep growing and get more aggressive..and I may need to find them a new home.

Not sure what type of fish they are. Where did you acquire them?

Fishmanic said:

Not sure what type of fish they are. Where did you acquire them?

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Got them at a large chain pet store - I think PetCo.

looks a bit like this species but I'm not sure

what did Petsmart show them as being?

It's a slow time of day on the forums. Check back tomorrow and someone here may respond if they are familiar with this type of fish.

Looks like an african banded barb to me.

emeraldking said:

Looks like an african banded barb to me.

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Me too.

brazosfish said:

I have two of these long fish with thin vertical black bands….they are almost 3” long now. They are slightly aggressive, but haven’t hurt any other fish yet. They do aggressively go after the frozen bloodworms I feed my other fish (Rainbows and Angelfish mostly), and they have eaten a snail I had.

What are they? I am worried they are going to keep growing and get more aggressive..and I may need to find them a new home.

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Your worries are more than justified. All cyprinids are shoaling species and that means they must have a group, and anything less than say ten is a serious risk for the fish. This can vary depending upon species, but too few (and two, three, four, five, six are too few) means increased aggression and a stressed fish that will slowly weaken and die before its time. Given your other fish in this tank, this is not a compatible fish anyway, so I would re-home them, not increase them.

Fishmanic said:

what did Petsmart show them as being?

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I don’t remember….I was restarting my aquarium after years in storage and bought about 20+ fish that day including two of these… I swear every 2 weeks they are larger….

Ichthys said:

Me too.

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Yes! That is it! Thanks! Interesting to hear about their schooling behavior. Looks like mine are full grown or on the large size….Glad to know they don’t become aggressive usually.

I don’t really understand about the schooling….I only have 2 (don’t want 6 of them anyway)….if they aren’t aggressive now - does the lack of a school make them more stressed / aggressive?

They did eat one of my large snails…

brazosfish said:

Yes! That is it! Thanks! Interesting to hear about their schooling behavior. Looks like mine are full grown or on the large size….Glad to know they don’t become aggressive usually.

I don’t really understand about the schooling….I only have 2 (don’t want 6 of them anyway)….if they aren’t aggressive now - does the lack of a school make them more stressed / aggressive?

They did eat one of my large snails…

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As I already tried to explain, shoaling fish like cyprinids must have a decent-sized group. This means close to 10 or more. This need is in the genetic code of the species. The fish expects to be in a group for safety, normal hierarchy, etc. Scientific studies have proven that fewer than 10 means increased aggression. Now we need to look at what "aggression" is here.

Naturally aggressive species become considerably more aggressive. I don't think we know why physiologically, we just know that it happens most of the time. More rarely the opposite can occur, the lone fish literally pine away, weakening and succumbing to various problems they would/should normally bee able to easily handle. Species that would normally be what we would certainly call peaceful will become aggressive. There are many stages to aggressive, but the fish in too small a shoal will exhibit aggression.

There is also a latency to feed from being in too small a shoal. This may not seem like a problem, but the fact is that it is extremely enlightening--a fish that is reluctant to feed is certainly under a considerable level of stress.

To be blunt about this...to deny a shoaling fish the number of its own that it expects is inhumane. If you cannot provide what the fish must have to be healthy and normal, you should not have that fish. This is why research is so crucial. Another member, @GaryE , posted a thread today on the subject of bullying, and it contains a lot of bang-on good sense information. All aquarists have to learn this if they want to be successful and have a tank or tanks of well adjusted, healthy and "happy" fish.

I've started to look at individual fish from social species as cells. The creature is composed of a whole bunch of individual units working together - foraging, on the lookout, signalling danger. They need to work together because one alone can't multitask enough to stay alive in nature. More and more, I look at my cardinals as just that, cardinals. It is a group of 26 right now, and they are a unit, not individuals.

It's a weird concept, because we humans like to count. The Sesame Street Count would hate my way of looking at 'shoalers', but it is more and more convincing to me.

I have some smaller groups of 5 or 6, because I couldn't get or afford more. More and more, I am thinking that if I can't breed them up to larger numbers I really shouldn't be adding them to my tanks. I'll try.

I know this sounds weird. But shoaling fish may have individual ways, and individual bodies, but are necessarily part of a very important (to them) group. Alone in nature, their lifespans can be counted in minutes.

Yes! My fish are over 3" and maybe getting closer to 4". I do think they are Acrossochelius paradoxus. Thank you! Hard to find much on them... I think they need a larger aquarium to swim in. Wonder if I get get the pet store to take them back. Not sure if they still want to school... they were not in a school that I remember... they act more like red tail black sharks and Baja sharks... but they are even quicker and even more active swimmers, darting around my plants with amazing speed and deftness... and they love feeding time they aggressively go for the frozen bloodworms, but so far haven't hurt any of my other fish.