Hi Shifty,
Based on your stocking list I would say that your aquarium is somewhat over stocked. You have to consider that Corydoras can grow to about 6-7 cm each and the Praecox Rainbow can also achieve quite a long length.
The fact that some of your fish are experiencing body rot and fin rot points to an ammonia issue which is commonly caused when too much food or fish or both is added to the aquarium. I personally think that you need to remove the top-dwelling fish that are dying to a new aquarium because if they become deceased in your current aquarium they can spread disease to the bottom-dwelling Cory's, usually giving them bacterial Popeye disease and fin rot.
Moving the dying top-dwelling fish would achieve 3 things:
1. It will reduce your aquarium stock to a more healthy level
2. Disease will not be spread around your main aquarium.
3. Reduction of the ammonia fluctuations, if there have been any at some point.
Based on your stocking list I would say that your aquarium is somewhat over stocked. You have to consider that Corydoras can grow to about 6-7 cm each and the Praecox Rainbow can also achieve quite a long length.
The fact that some of your fish are experiencing body rot and fin rot points to an ammonia issue which is commonly caused when too much food or fish or both is added to the aquarium. I personally think that you need to remove the top-dwelling fish that are dying to a new aquarium because if they become deceased in your current aquarium they can spread disease to the bottom-dwelling Cory's, usually giving them bacterial Popeye disease and fin rot.
Moving the dying top-dwelling fish would achieve 3 things:
1. It will reduce your aquarium stock to a more healthy level
2. Disease will not be spread around your main aquarium.
3. Reduction of the ammonia fluctuations, if there have been any at some point.
