Is There Any Way To Find How Old Fish Are?

I am not exactly a fish person but I have taken care of quite a number of fish over the years in either small tanks or fishbowls. I have taken care of some Angelfish, various tetras, many guppies, a black molly, some goldfish and some other freshwater fish that I do not even recognize. Here in our country, pet fish can be bought out on the streets outside schools and churches at very low prices. The vendors unfortunately do not know what kind of fish they are.

Anyway, I have always wondered if there is any way to find out how old fish are. If they are born in your tank it would be easy to jot down their birthday but when you buy them outside, the vendors are of no help. I thought to ask here since it seems most of you are experts in fish. I hope someone can answer my question.