My son's done that too. We have 'The Edge', 'The Deep', 'The Shallows', 'The Cube', 'The Pool', 'The Green and Black' and 'Gormok's Pad'
Most of the fish, but not all, have some sort of 'name', even if it's a collective one!
Gormok, the oscar
Six, the striped talking catfish
Spot, the spotted " "
Half Tail, the syno
Gorky, the black angel
Mrs Whippy, the royal whiptail
Russell, the BN
Weekly, the L052
Syn, the gibbi
The Lads, the male Endler's (the female Endler's don't get named
)
The Swarm, the tiger barbs
and then there's Bob, Bob, Bob, Bob, Bob, Bob, Bob, Bob, Bob, Bob, Bob, Bob, Bob, Bob, Bob, Bob, Bob, Bob, Bob, Bob, Bob, Bob, Bob, Bob, Bob, Bob, Bob, Bob, Bob, Bob, Bob, Bob, Bob, Bob, Bob, Bob, Bob, Bob, Bob, Bob, Bob, and Bob, the green neons
None of the rest have any kind of name, they're just 'the zebra loach', or 'the silvertips'