angelfish questions

i have 4 angels 2 are a little bigger than quarter size(their body size)and the other two smaller than a quarter, i need to know how old they are about and when can they start to breed if i think i have a pair? also if they are a pair (they are in a 15 gallon tank by them selves and when we bought the other two and put them in there the one was gaurding the other one, so we put the two new ones in a different tank) do they do that sometimes even though i dont think they are old enough to breed? i have done research and i cant find to much about breeding ages and stuff.

Angelfish can spawn when they are as young as five or six months, but it's rare and seldom successful. If you want to get a spawning pair, you'll need more and bigger aquariums. The most common way to get a pair is to put a half dozen or so juveniles in a 55 gallon aquarium and wait for them to pair off. When that happens, remove all the rest of the fish, and let nature take its course. Only when they are ready to spawn will you be able to see their spawning tubes (just behind their ventral fins), and the gender difference is pretty obvious. It's important to check, because two females will sometimes spawn just to unload their eggs. If you over crowd angelfish, they will have more territorial disputes and a greater chance of getting sick. The rule of thumb is ten gallons of aquarium space for each mature angelfish. If you're interested, I can make some more suggestions about aquarium procurement and setup.