Since always? There is nothing about a grinding up a lump of magnesium silicate that makes talcum powder's uses only work on animals. There are also dozens if not hundreds of human medications that work great and are commonly used on animals.
And this is before we get into the fact that humans ARE animals.
There are a lot of breeding tables for it on the internet. It's pretty straight forward. You have body type and fin type, each has a list of 16 or so different types. When breeding the fin numbers get averaged to give you whatever fin the resulting number is. Same for the body. So there are dozens of ways to breed different fish with the exact same resulting fish.
I think you need to shut the game down then advance the time then start it up again, I don't remember exactly. It's a pretty small game though, so it loads quick.
Might just need to save and reload also.
The game does work in "real time" which means it keeps track of time using your PC's clock. Breed some fish, move time forward a couple hours until the fry are adults, move time back,breed fish again, move time forward a couple hours until fry are adults...2 minutes time you have piles and piles of adults to sell.
$450 seems expensive but not a ridiculous claim, I could easily see that being the price at an average or small petshop. The recommended retail price in the US is from the looks of it is about $260NZ. NZ prices are frequently 50-100% more than that.
Cheapest way long term or cheapest way short term? Short term just make sure it's insulated as well as you can and throw a couple heaters in it. Long term...Probably you'd want something like coils of hose on a roof to be heated by the sun or something along those lines.
Get a whole bunch of peat in a big bucket and pump water through it? Will turn the water brown though, but it's already bright green, isn't it? May not be noticable.
It's commonly done with long, fine haired cats, stops the fur from sticking together a bit so they look nice and fuzzy. Especially in places like behind the ears. Works to pretty them up for showing.
Make sure you check the fish for odd scars and implants. Goldfish at least won't stress over the missing couple days from their alien abduction and have a short enough memory they won't remember the probes.
I don't think the slight green tinge of the glass is an issue given you're taking the pic through the thinnest direction. You're pretty much worrying about #39 of difficulties with taking pictures of fish. And probably the easiest to correct with photoshop.