Good advice needed to save Corys

Hello Everyone,

Our 55-Gallon tank finished cycling about 2 months ago and we added six(6) Corydoras Aeneus. A week later we added four(4) Lapidochromis Caeruleus and four(4) Microgeophagus Ramirezi. After about a week an a half all of the inhabitants of the tank appeared to be getting along just fine. We then decided to add four(4) Pseudotropheus Demasoni. All fish in the tank were 1" - 1.5" in size when addedd to the tank.

A week ago we noticed that one of the Corys was not active, but just laying on a plant leaf. Upon closer examination we found that his tail fin was almost completely gone along with portions of his dorsal fin. We removed him from the tank an put him in a quarrantine tank that we have set up. Three(3) days later, we found another Cory in the same spot with nearly all of his tail fin gone. We thought it might be fin rot disease at first, but none of the other fish showed any signs of losing fins then, or now.

We assumed (but never saw) that the corys were getting nipped at by the newest inhabitants (Demasonis). We removed all of the Corys from the tank(55G) and found that three(3) of the six(6) had some form of fin damage. All three(3) of them died we suspect from the shock of being chased and nipped at. The three(3) that died also happended to be the ones that have grown the least since we purchased them. The other three(3) are not as active in the smaller (5-gallon) tank as they were in the large tank. They are eating and they look ok, but they are not darting around as they did in the larger tank. I wanted to let them grow some more in the small tank and then place them back in the larger tank hoping that with more size, they might be better able to defend themselves better.

Are we taking the right course of action? We are open to any and all suggestions to help me to save these fish and keep them healthy. We were told that we could keep Corys with the other inhabitants of the tank. Is there anyone else who is successfully keeping this combination of fish in a community tank? Thanks in advance for all of you help.

Thanks for your response wetmanNY,

You're right, the other fish may well be innocent. The three(3) Corys that I have isolated right now, appear to be doing well. I have not seen any appearances of fin erosion on any of the other fish. Should I still treat with Melafix?

Ammonia levels are 0.0, Nitrite levels are 0.0 and Nitrate levels are <5. I check the water weekly and do a twenty(20) gallon water change weekly. I don't believe the ammonia or nitrate stress is the problem. Could very well be bacterial or parasites.

Thanks for all of the input.

latazyo - It may be that the rams are nipping at the corys, but I have never witnessed it myself. I never noticed the corys fins gone until after I added the Pseudotropheus Demasoni. The corys were the first inhabitants of the tank.

famman - When we initially bought them, we bought six(6) of them and put them in the tank together. Now three(3) of them have died mainly through losing vital fins.

Pat - you are right. It did stop when I moved them. I want to let them grow more and reintroduce them back into the larger tank when they are larger. Two(2) of the three(3) seem to be growing faster than the othe one. Would it be ok to try reintroducing them to the larger tank once they have grown, or should I just look to keep them in a seperate tank from now on?

Thanks everyone.

Thanks for all of the input.

latazyo - It may be that the rams are nipping at the corys, but I have never witnessed it myself. I never noticed the corys fins gone until after I added the Pseudotropheus Demasoni. Then I noticed one of them was just lying on a plant leaf instead of swimming around. That's when I noticed his entire tail fin was gone. The corys were the first inhabitants of the tank. The really puzzling thing is that none of the other fish have any damaged fins. One would think that if there is a nipper in the tank, how could they resist those beautiful ram fins?

famman - When we initially bought them, we bought six(6) of them and put them in the tank together. Now three(3) of them have died mainly through losing vital fins.

Pat - you are right. It did stop when I moved them. I want to let them grow more and reintroduce them back into the larger tank when they are larger. Two(2) of the three(3) seem to be growing faster than the other one. Would it be ok to try reintroducing them to the larger tank once they have grown, or should I just look to keep them in a seperate tank from now on?

Thanks everyone.