what is costia in fish
Â· Tropical Fish Food. Costia Costia is one of the many fish diseases that are caused by protozoa. It is a somewhat rare disease that is relatively easy to cure if your fish becomes infected by it.ronema marinum-Information on diagnosing and treating Uronema marinum. Velvet-Information on diagnosing and treating velvet. Costia is one of the many fish diseases that are caused by protozoa. It is a somewhat rare disease that is relatively easy to cure if your fish becomes infected by it.