You could put the following:
3x Neon Tetra
or...
1x Betta
The best kind of pond pump for a two hundred gallon koi pond is an alpine pond pump. This would work best for this size pond because of it's size and power.
One Gallon? Only a Betta. Most anything that's small enough for a 1g is to active for one. A micro-tank can be absolutely lovely though if you plant it really well, get a rams head snail to keep waste down, and pick out a really pretty Betta.
Almost no fish can live without a pump. Unless you don't care if it live do four hours. A catfish can live in a 5 gallon tank for maybe a month. Then you would have to buy a bigger tank. The smallest catfish grows to about 5-6 inches. A good thumb rule: 1 inch of fish per gallon. I hope this helped! :):)
because its an octagon around the 1900s
I have a 28,000 gallon pool and my pump is 1hp. Works fine.
Approx 400gph return pump
Between a 500-gallon-per-minute pump and a 2,000-gallon-per-minute pump.
Depends on whether or not you have aeration (an air pump). If no aeration, then you shouldn't put more than 2-3 fish "inches" (total inches of fish) in the aquarium. If you do have aeration going, then you can double this amount and have up to 6 inches of fish.
Condition?
a fish filter cleans the water and a pump pushes it through a fish filter cleans the water and a pump pushes it through
Depends on what you have.
Wall hanger to 1000 USD or more depending on specifics.