Maybe it's a longshot..but...

[Requiem]

I have a pair of black tip sharks in my aquarium along with a few other freshwaters. (A few platy's, a fancy male guppy, and some plecostemous.)
I noticed in the last month or so, that although my sharks/catfish were the same size when they were purchased, one is now almost twice the size of the other one.
Tonight, I noticed the smaller of the two having a peculiar bulge in it's stomach. From what I read of the site, it sounds as if their breeding in captivity is rare, and fairly unlikely. But at the moment, the smaller one is exibiting a behavior I've noticed of larger wild fish such as salmon.
The smaller has been trying to hide beneath one of our fake plants, and almost looks like it's attempting to dig a hole in the gravel.
I know it's a bit of a longshot, but these fish I bought from our local Walmart Supercenter, whom informed me this evening that they just throw the fish in the tanks when the shipment is recieved...and don't seperate the sexes.
So...now I'm keeping an eye on sharks I'm not well acquainted with keeping, and I have no idea what to do!!
Any ideas? Lol.
I never bought them with the intent to breed them. I just bought two of each kind, thinking that they'd aclimate better with a tank mate of the same species. (And I thought...same sex.)
Thanks a lot,
Michelle F.

[blackwolfXKAV]

are your parameters in check?

(in the case of non-breeding)

sounds like this could be interesting, keep us updated..

Good Luck,
Black_Wolf

[H3D]

What size aquarium do you have all these fish in?

[Tommy Gun]

I am going to assume here that what you have is more along the lines of a Bala shark rather than a black tip shark which is a saltwater reef shark...correct? I googled the name black tip shark and not freshwater fish came up within the first three pages anyways.

So, these bala sharks, assuming that is what you have are going to get big and the less dominant one is going to grow slower than the other more dominant fish. You can avoid this somewhat by keeping them in groups of four to six, but they get really big and so it would take a big big tank to keep them.

Just as well, bala sharks are not typically bred in captivity like you point out...however they are egg layers and so I do not think that the bulge in your fish is from fry in its belly area. It could be that the fish is having problems digesting food or is constipated for the lack of a better term. You can try to feed it some mashed or squished peas (frozen variety, but thawed out of course) as this will help clear out its system.

So hopefully this helps and I am too far off base with the bala shark assumption.

[5TankHarmony]

I saw two things wrong with that. Number one is that you said you have two (we're going to assume bala sharks) with a fancy guppy. That just sounds like a disaster waiting to happen. Number two is that you said "a few plecos". Unless you have a VERY large tank, that just isn't going to work. But anyway, welcome to AC! And I hope you can learn a few things while you're here- or perhaps we can learn somehthing from you...