6 small plecos died one day!

[TizMyLife]

I had 7 plecos about 2 inches long. 4 in one tank and 3 in an adjacent tank both with guppies. I have been feeding them algae wafers and cholla wood.

This morning I went to feed and 6 of them were dead, floating on he surface with their stomachs looking like they were eaten away. Wha could have happened? The guppies are all fine and the remaining pleco appears fine! What do I do?

[Colu]

They could have died and snails have started to eat them

[Sapere_Ceta]

I would test the water and see how much ammonia, nitrite, and nitrate could be present. You could definitely have an ammonia spike from these deaths. A large volume water change would be good to do afterwards. If there is an issue with any of those parameters, test again maybe 10 minutes after the water change. If not, I’d start checking other parameters to see if they’re okay, checking equipment to make sure nothing is malfunctioning, start observing the tank for signs of illness, and so on. Think of it like a “what could it be” list, and go down the line until you might have a couple options that seem probable, after the others have been checked off. 

I agree that they were probably picked at by snails, or even possibly by the remaining fish in the tank as well. I wouldn’t worry about that, particularly. Body degradation in fish can occur at a faster rate, and especially so when other fish or inverts are present to pick at it. 

 

[Mr_Manifesto]

they being out competed for food?  Sunken bellies on all of them could mean internal parasites or they were just starving.