im not sure how many gallons it is, but its 20" wide 10" thick and about 11" tall.
they are two small fantails about 2 and a half years old. is it big enough to breed them? IF they breed should i lower the amount of water and to how much?
i think i have a good filter, it has three layers, cloth filtering, charcoal(or what resembles it) and a little bit of rock salt to clean infections and keep them healthy.

This isn't helping your question but u have a 10 gallon tank lol.. I measured mine to see if it was the same

Noahnjm