You have male guppies and black neons. Didn't you get the black neons to eat the baby guppies?
re: the 3 male guppies, the smallest all yellow one has a funny shaped head and flared gills. You might want to treat the tank with Praziquantel for gill flukes & tapeworm, and Levamisole to get rid of any intestinal round or thread worms.
re: the 3 male guppies, the smallest all yellow one has a funny shaped head and flared gills. You might want to treat the tank with Praziquantel for gill flukes & tapeworm, and Levamisole to get rid of any intestinal round or thread worms.