2 fish dead!

[AmyKieran]

Hi, I have a 50g Malawi tank that has been established 9 months, currently has around 40 Malawi and 5 catfish. This morning I’ve came down to 2 fish dead. One of them is right in the middle of the sand, the other is under rocks. I have tested tank water and the parameters are below. I’ve removed both of the fish from the tank. Amy guess why? And what to do now

Thanks

Ammonia - 0
Nitrite - 0
Nitrate - 15

 

[Deleted member 149562]

Has there been any increased/abnormally higher aggression tween the fish in the last few days or weeks that you have noticed?

 

[AmyKieran]

Has there been any increased/abnormally higher aggression tween the fish in the last few days or weeks that you have noticed?

No, I have noticed that one of the fish that died has been sluggish and slow, still eating but slow. The other one, I hadn’t noticed anything

 

[Deleted member 149562]

No, I have noticed that one of the fish that died has been sluggish and slow, still eating but slow. The other one, I hadn’t noticed anything

Roughly how many days has the one that died been "off"?

Are there any obvious or easily missed injuries on either fish or signs of illness/disease?

 

[AmyKieran]

Roughly how many days has the one that died been "off"?

Are there any obvious or easily missed injuries on either fish or signs of illness/disease?

Maybe a week, the fish has a slight bulge on its stomach

 

[GaryE]

As mbuna grow and get more and more territorial, deaths become inevitable. 45 fair sized fish are a lot, even for Malawis who love crowds. If I were running a 50 gallon, there wouldn't be more than 25 mbuna and catfish in it. Honestly, as harsh as this sounds, either the fish will reduce the numbers or that kind of crowding will allow a disease to spread. Let's hope it's ordinary mbuna murder.