Helpful Marcos , neither the neon or the flying fox are in the fish index (last time I looked)
neons, I assume (possible wrongly) same as cardinals, females slightly large, and broader, more pronounced when seen from above
flying fox, as with the rainbow and red tail sharks Guess . Hypothetical from red tail rules - Female, may be larger than the male (at full growth LOL) but males as a general rule should be more slim lined and the females should be be rounder, VERY pronounced when with egg. Males may also have a triangular dorsal with females having a more angular tip. These are guidelines only and are in no way hard or fast rules.
thanx that has help quite a bit because one of me neons what i have is more rounded on its belly and one of me sucking loaches is longer than the other and i have just some leopard danios and a pleco so how would u be able to tell on a leopard danio