Knowing fish, I wouldn't rely on this information. The chance of disease and everything is just way too high in that small of a barrel. I can just picture 40 catfish trying to even move around in a 55g anything. The oxygen would be depleted in no time, the waste products, etc. Even with the minor water changes they're talking about, it's just insane. I mean, if anyone wants to try it, by all means let everyone else know, but based on my experience of fish, I just see a barrel full of sickly/dying/dead fish. Not to mention it's still not self-sufficient. When TSHTF, you'll be figuring something else out entirely, because so many unsufficient necessities come into play for this to work (in theory). Electricity... Even if you have the solar panels, what happens when the pump burns out? What happens when the solar panel gets cracked? No warranties are going to be around, right? We're all assuming SHTF you're completely on your own with possibly neighbors, but no big corporations, or access to such, right? What about the water? If you have no access to the water to fish out of, then how are you getting water when your well pump craps out? Also what I don't understand is, if people are against chickens being crammed in cages in commercial operations, then how is this any better? Guess I just don't understand the mentality of the operation.
If we're not talking about SHTF, it's still not reasonable. You're using more money to put into the product, and if money isn't the issue, why not just buy the silly swimming pool and be done with it instead of spending thousands on solar panels or water or whatever?