So ive had 6 corydora sterbai in my tank which appear to have red on their sides as seen in this picture
5 of the smaller ones have predominant red colouring. This is not due to ammonia poisining as the levels in my tank are both 0 for ammonia and nitrite.i also have 20 cardinal tetras in my tank which love life. All the fish in the tank eat when they are fed and are continuously moving.
My question is that i have some discus fish at my local fish shop on hold for the next week is it safe for me to put them in? Or is this red some sort of disease?