I suppose, fish ponds do take up a lot of space, so having an alternate way to breed them a little bit could be a decent addition... but looking at the fish tanks we already have, one that could have enough space for breeding would have to be BIG as far as inside stuff goes. I mean, it would need to hold the fish plus more as they reproduce... how much space would it save if you're needing a shed to produce 5 fish, you know?