How many tetras can I fit in a 20 gallon tank?

You could get a couple hundred in there if you don't care if they're dead. But if you're looking to put the maximum number of healthy fish into a healthy ecosystem then I would not get more than 20. The rule is "Not more than one inch of fish per gallon of water".

If you follow that rule then you'll be ok. You should make allowances for growth, however. You said they can grow to 2 inches per fish.

If they do grow that big then 10 will be your number. You might want to try 10 first and if they don't grow then consider adding a few more, but don't exceed 20. I hope this helps.

Good luck.

If they are 1 inch then 20 but if 2 in I wouldnt go past 10 or 11.

The overall consensus that I came across when setting up a new 20 gallon tank was one gallon to each inch of fish. So, if you can have 20 fish that NEVER get more than an inch. 10 fish that will grow to 2 inches.5 fish that will grow to 3 inches and so on.

We have mixed fish right now. Calculating their adult sizes allowed us 2 mollys, two glass shrimp, one guppy, 3 cardinal tetras, and 2 glass fish. Different tetras grow to different sizes.

The ones we have will never reach more than about 3/4 of an inch but we rounded to a whole inch to make room for error.

I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.