I've thought carefully about getting a couple of 1000gal above-ground kiddie-pools (or digging 5000Gal shallow tanks) and importing 1.5" clown loaches 1000 at a time. Temperature's not an issue, and apparently there's a pretty good market for 4" fish- which in that size system with good wind-driven filtration & lots of water storage and a high-bug & snail diet we could get to in 18-months.
Ultimately it'd be a labour of love as profit would be a little...slow and shipping costs would mop up much of the gravy, but considering an initial price of maybe $2.5-3/fish (with importing) and wholesale (selling) price of maybe $15-20, it might add up. Plus there are Govt farmer's incentives.
Also thought of combining this with rays. Not nearly there yet either way.
At the end of the day, the best money seems to be in Koi for either breeding or grow-out. Unfortunately I am not a fan, so for a hobby-business... no.
A