Bump / growth on head of corydoras?

[Essjay]

According to Tetra's website, AquaSafe Plus contains
"Polyvinylpyrollidones, Seaweed Biopolymers, Organic Hydrocolloids".
Polyvinylpyrollidones (PVPs) are intended as slime coat promoting agents. I wouldn't use this product either.

 

[ninky]

It looks like an excess of mucus cause of something in the water (or other parameters than they were in).

Hard to say. It started off as a sort of white patch. Some reading suggests it's diet, excess of protein and not enough vegetable diet - so I went back to feeding wafers more regularly. I don't think this is the case as it was just a few days at most and consisted of mostly Fluval bug bites, a catfish blend of Shrimp & Krill (with spirulina), Hikari Mini Wafers, and I'll provide frozen shrimp shortly. I also fed occasionally Sera O-Nip Nature which I had been given from the store and they go crazy for it - but I'm not so crazy about some of the ingredients and it is very messy. The only benefit is that it's soft and optimal for fish with small mouths (but takes a while to get to the bottom.)

 

[ninky]

One new item I noticed about these cories. To clean the water I added an extra 80 GPH pump that I stuff two filters in there with a very fine polishing pad like media at the end that removes an incredible amount of physical stuff in the water. I have two other filters that should be fine (a small hygger that I stuff with purigen with filter floss at the opening and another with rotating media using air too that has foam at the bottom.) But this shoots a jet across the depth of the tank (back to front) as I didn't want it to run the whole length. The fish absolutely love this. This swim up into the stream and love to be shoved against the glass and pushed across the width of the tank surface. Its hilarious to watch.