I have a well established (1.5 years) 10 gal tropical community with 2 Mickey Mouse platys, 4 neon tetras, 2 guppies and 1 mystery snail. I went on vacation for 10 days and used a topfin fish food feeder block. I did about 25% water change the day before we left and the day we came home. Temp was constant and lights off, but window shade open(indirect sunlight). 1 neon died a few hours after we came home. 1 platy appeared very ill the next day, but improved. 1 guppy appeared very ill and died yesterday. The other platy appears sick today. There are no white spots, but fish that appear sick or have died have been resting on the bottom, having trouble righting themselves, and not eating. I observed a clear to whitish poop from the surviving platy. All water testing (api master kit) has been good with nitrates slightly high when we returned as expected(40-80ish). Is this most likely bad food? Clogging their system and leading to bouyancy issues? I don’t want to treat the tank unless it is absolutely recommended. But I really don’t want to lose them all! Any help is appreciated! They are my 8 year olds fish, and death is hard! Plus I really like them too!