I’ve had my male guppies since October and I lost my first today. He has been swimming jerky for a few days and I noticed he looked kind of lumpy yesterday. Water temp is 78°, ammonia and nitrites are 0, nitrates are 10, ph is 7.2. It’s a 38 gallon tank with guppies, tetras, danios and 3 corys. Today I found him minutes after he died and he was all bent up like crazy and had a dark spot inside his abdomen. I’m including pics to show both. The rest of the fish look ok and are acting normal besides one female guppy who has looked tired and hollowed out since her last batch of fry a month ago. Ideas? Will anyone else catch something?