Cory Death: What Could Have Killed Him?

[soritan]

My tank is cycled, over 6 months old, and stable. ammonia and nitrites are both 0, my nitrates are 20ish (can't read those stoopid color charts). My Schwartzi cories have been fine, exhibiting no symptoms of sickness at all.

Today I came home to find one dead, atop a plant, with a red spot in the middle of his belly, and another at his gills, but no actual leaking fluids.

Could this be an internal parasite, or would these red spots be sort of like fishy bruises, and he suffered blunt force trauma from my female betta?

 

[tttnjfttt]

It sounds like he had a bacterial infection called septcemia. The main symptom of this is red streaking, which it sounds like your fish had.

 

[soritan]

He wasn't streaked red at all, previously. He's a brilliant silver and black fish, red streaking is very easy to see on that background.

Could he have developed septima suddenly while I was at work?

 

[tttnjfttt]

My guess was that it just wasn't noticed earlier. If he was hiding, or you saw him at the wrong angle, it could be missed. However, it is possible he developed it while you were at work.