killer harlequins?

[j55]

ok, i got a rekord 96, glass cats, syno.nigriventris, leopard danios, cardinals, 1 golden gourami, a high-backed headstander and an ancistrus

and recently a shoal of harlequin rasboras,

i have not had any problems with that set up. But the next day my gouramy had had no tail, and no fins and was dead, as was a leopard danio that had the front half of its body and just bone for the rear end!
The next day (today) there was a harlequin dead and a cardinal, both dead via physical abuse, anyway the only thing in there big enough to do such damage is the high-backed headtander, but it has never been aggresive to anything else before, why now?

Have you tested your water? What were your ammonia, nitrite, and nitrate readings?

Is your tank 96 gallons?

I own four of the marbled headstanders or abramites headstanders. They are peaceful, but as adults they become nippy. They will pick at other fish or just at each others fins. Other than that they are good fish and can be mixed with a variety of fish

That is what someone wrote about them on this website.

I read through other profiles for the Headstander and it seems that they can be really nippy to other fish, especially if kept alone. I would guess that the Headstander is the culprit. Harlequins are really peaceful and not nippy at all IME, so I am 99% sure they wouldn't kill your other fish.

[Durbkat]

No its 96 liters JOM, thats a tank in the UK.

Thats what I thought, but wanted to be sure. So thats around 26 gallons....not very big for that list of fish. How many of each fish do you have j55? The reason for the aggression may be related to overcrowding, if in fact you are overcrowded.

[j55]

sorry about that, i will specify better next time,

anyway how can i prevent this?
It's an adult so it cant be mixed with others of its own kind?

Should i just see what happens and let nature take its turn?

[Durbkat]

How many of each fish do you have?

[j55]

sorry about that, i will specify better next time,

anyway how can i prevent this?
It's an adult so it cant be mixed with others of its own kind?

Should i just see what happens and let nature take its turn?

I saw in another post that you have a bigger tank to be setup. Is there anyway you could move the headstander to the bigger tank and put some non-long finned, semi-aggressive fish with it? That would make sure it didn't nip other fish and that similarly aggressive fish could hold up to the headstander.

I saw on one of the profiles that a 4 foot tank is recommended. You should google the name and get more info on this guy. I don't think the tank you have him in now is big enough.

I suggest you move him, if you want your other fish to have a chance.

Also, could you post the number of fish you have of each type? I'm afraid you could be overstocked and overcrowded. That may be why the fish are a little more aggressive than normal. The headstander would be the most aggressive fish in the tank, while the others are peaceful. Its would be best to remove him to a bigger tank with more suitable tankmates.

[Cichlid Man]

It's not your fish that's the problem, it's your water. Is your tank cycled? Your tank may be polluted or have the wrong parametres, that's what's actually killing your fish. Your fish die and then the others eat the remains.
Also if a fish is a bully, it won't take long for you to notice it.
Best test your water for nitrite, ammonia, and ph. If the nitrite and ammonia are too high, change the water to dilute the toxins.

[j55]

ATM i have
1 glass cat (i know they are supposed to be in at least 3's but it wouldnt eat whn in a group, only when it is by itself)
1 ancistrus
3 synodontis nigriventris
4 leopard danios
3 cardinals (more have been eaten)
1 high-backed headstander
8 harlequin rasboras


I am putting a polypterus delhezi in my 4' so i dont know if my headstander will be ok with that,

[j55]

no my water is fine, and the fish that were dead has chunks out of the side of them etc.

[Lupin]

Originally Posted by j55 no my water is fine, and the fish that were dead has chunks out of the side of them etc.

We daresay you post the water stats. Without it, we'll never know what's wrong with your tank.

[Cichlid Man]

Originally Posted by j55 no my water is fine, and the fish that were dead has chunks out of the side of them etc.

Yeah that's "fine".

[Durbkat]

Exactly, as what you may think is "fine" may be really bad.

I am assuming the tank wasn't cycled...because you haven't stated otherwise. Do you have test kits for ammonia, nitrIte, and nitrAte? If so, could you post your readings so we can be sure they are "fine".

If the tank wasn't cycled, you probably threw too many fish in there at one time. I also think the tank is a little overstocked.

How often do you do waterchanges and how much?

It could be aggression or the water. The ammonia levels could be high and that caused the fish to die...then the others pick at their remains, which is why you see chunks out of them.

Did any of the fish that died have any signs of fin nipping (chunks out of their tail) before they passed?