Half-breed Convict gone insane?

[FrogLover2006]

I have a 55 gallon tank currently housing 3 oscars, 1 half-breed convict and a pleco (sp?). The convict used to stay in his own little corner - but now seems to be on a murderous rampage. He is about 5 years old now and attacked our Albino Oscar until he killed it. We noticed them fighting a lot but never thought anything of it... When we found the albino in the morning he was missing most of his scales and the convict was STILL attacking it, even though it was quite dead. Now he races back and forth through the tank and attacks the other oscars as well as the pleco. He's got a few cuts and scrapes from the plecos spines but is still aggressive. The water is normal and has been changed recently, and they are being fed well. We're in the process of isolating him - we've got another tank being cleaned and set up for him. Can fish go insane, or is something else causing this? Since he's been with the Oscars for a few years now, it seemed unlikely to me that he would suddenly become vicious towards them for no reason.

Also, anyone know where I can find another albino Oscar? It was my dad's favourite and he's a little upset about it's untimely death.

[joylynn]

You are probably a little overstocked. Everything I have found on Oscars says the smallest tank size for an Oscar is 70 Gallons. Also, what are your water parameters? With that many larger fish there could definitly be issues with the water starting that can cause changes in behavior. Convicts are listed as agressive fish so any overcrowding he feels is probably going to result in injury or death for the other fish. He may just be starting to feel that way now after years of peaceful behavior because the other fish are growing and starting to take up the space he feels is his.

[S.A.]

ditto.
The tank is overstocked and territory becomes a HUGE deal. Your oscars may be on the smaller side now, but they require a great deal of room, so do convicts.

[FrogLover2006]

I have two convicts about 3" and one probably closer to 5". The covict is about the same length as the larger oscar. Pleco's about 8-9" long. I know the water quality is fine, it was just changed recently and was good then. Filters are working and their internal componets were replaced recently as well. Temperature is about 75 - higher than normal due to the summer heat but still in the safe zone. I also just noticed the convicts got some yellowing along the top of his sides - maybe an infection? I don't know much about illnesses.

EDIT - I've also had the convicts 2-3 years now... they don't seem to have grown much since purchase, same with the convict, reached cuurent size bout a year ago and hasn't budged. Pleco growing nicely though.

[S.A.]

Not enough space is probably the main issue. Does your convict have a hidey-hole? Is there anything to break the line of sight, although in a 55G with those fish it is still too many.

edit: You may have had them a while and they should be much bigger (oscars that is, how big are they?). Stunting occurs when they are not given the proper amount of space.

[DaisyTattoo]

The way you are talking about your water change leads me to believe that you don't do them often..perhaps monthly??? In any case, you should be doing at least 20% weekly, probably more in your case. You say your water is "fine" what does this mean? How do you define fine? Have you tested your water for nitrite, nitrate or ammonia? I'm not trying to be mean, but these things are very important and seeing how new you are to the site, these things may be new to you. Look into getting a test kit. Aquarium Pharmeceuticals Freshwater Test Kit is wonderful. Print of petsmarts online price and take it to your local petsmart and they will most likely match the price of 13.49. THat is a great deal. Instore it costs 27.99 without that printoff. Yes, you should get another tank if you plan on keeping all those fish. This is probably just the beginning of the aggression. If you dont move them, you will have more dead fish.

[joylynn]

"Changed recently" and water parameters are fine is a little imprecise, do you have a water test kit to find out the actual parameters? I am still pretty new to this hobby but anyone who tries to help is going to want to know the ammonia, nitrite and nitrate levels for sure, pH and kH if at all possible and how often and what percent you are changing your water out. With that being said, I am still pretty convinced you have territory issues going on and if your convict is showing signs of illess he is stressed either from issues with the water parameters, territory or both.

[FrogLover2006]

My dad takes care of the tank most of the time - So I'm not completely sure. He usually does about a 20-30% change weekly and a complete change(clean the pipes and stuff too) monthly. That was about 3 days ago, it was conditioned as well. The Convict has a corner he usually stays in (we have a display tank so it's a lot longer than it is tall) and we have little pipes for each fish as well as fake plants for them to hide behind (real ones are a lot of work and we're afraid they won't get the right care)

[graphicdesign_r]

I'll agree with the consensus that you are overstocked.

I'll also be abrupt enough to say that it not "fine" and you should do somthing about it (return fish or get more tanks) and properly take care of your pets.

You should not replace the albino unless you get another tank that is appropriate for your stock at full adult size (like one twice the size you now have or larger).

Your convict is responding to the overstocking, and may also have breeding stress, which basically means he is looking for a place to mate and will drive fish out of his territory in hope of nesting (even is a female is not present I've seen older fish become territorially aggressive, suddenly attacking other fish and displaying mating colors - not sure if this extends to convicts!).

Good luck!

[FrogLover2006]

Thank you all, I shall definitely look into it. The breeding stress sounds plausible to me, it is that time of year and he seems to be picking up rocks, moving them and sucking them off. (We had another convict like him years ago almost die from getting a rock stuck in his mouth while they were competeing for the red devil we owned...) The other convict and 2 red devils died and were replaced with the Oscars. I'll move the convict and get tested, and hopefully this will resolve the situation. I shall also look at a bigger tank. Thanks!