me and my dad are picking up a 100 gallon 6 foot aquarium(If we think it is not old and has a chance of leaking) It ia 19 inches tall, 19 inches in depth, and 6 ft long! I have a Petsmart FH in a 40 gallon growout by himself. I was thinking of paring him up with a midas or a other FH in the 100 gallon. Are FHs visualy sexable without venting? If not should I buy a few FHs and use the ones that pair up? Help!