freshwater aquarium fish

Question
We have two albino algae eaters, two anglefish, along with several other fish in a twenty gallon tank. Recently we've noticed that one of the angelfish is far larger than the other. The same can be said about the two Algae eaters. Why is this happening?  

Answer
A 20 gallon tank is far too small for Angelfish or Algae Eaters: they need at least double that size to thrive. What is happening is called Stunting; where a fish, or all the fish, stop growing because of lack of space. I am afraid the only thing you can do is rehome the fish, and get some smaller fish such as Tetras, or buy a 40 or 50 gallon tank for them.
Best of wishes,
Kathryn