Hi John, you ask if there is anything horribly wrong with your tank. Well, I don't know where to start! If you have kept fish as long as you say you have you ought to know the shit is going to hit the fan fairly soon. All is well now but all your fish are very small and have not reached maturity. When they do...
The guppies will be eaten by the sharks, gouramis and sailfins.
Speaking of which, you should not put ordinary mollies in with sailfins as they will interbreed. Mollies also need salt in the water.
The small angels will probably get beaten up by the larger ones.
The red tail sharks had better be different sexes or you will lose one of them as well.
I don't know enough about the other sharks but the silver ones will grow too large for a 3ft tank. If they are not killed by the others first.
The blue gouramis tend to be stroppy and one female to 2 males is asking for trouble. She will be dead before long too I fear.
Serpae tetras are shoaling fish and as such there should be at least 6 of them for them to be comfortable.
The kissing gouramis grow up to 30cm (1ft). They alone would suit that sized tank without anything else in it!
I'm sorry, but you did ask!
Please consider rehousing some of these fish!