will say a lot of things. Literally take everything they say with a grain of sand (just dont pay for sand at the LFS
Granted as I preech, the hobby is about the observer, not the inhabitor.. if it was about the inhabitor I'd leave the fish in the ocean. However, given that idea - there is also reason. You could possibly get away with the yellow and blue but it may be rough on them and the blue will probably perish. You could technically add all of those fish if you wanted but it would probably be best if you kept either the yellow or a blue and gave all the rest to the LFS
for store credit. Use the credit to buy filtration devices and possibly another fish or two that would be more appropriate for a 55g -- like a firefish or something.