However I read that with the zebras, the females have 0-3 eggspots and males have 4-7 and he has 4..
Not true either. My two grown females have at the least 8 egg spots on their tails! With Red Zebras, most of the time you can tell by shinning a flash light on them. If they have a blue sheen to their fins and body, its most likely a male. Females may have a tiny bit of blue in the fins, but males have it in the body and dorsal fin. Once they are adults you can see the blue all over the male without a flashlight.
Egg spots on males tend to be bigger and darker, but really do not show that way until they reach about 4-5". My Acei male only has two egg spots, and my big females have more than 5. But, his are bigger and darker than theirs. I have noticed that the males spots really don't become very pronounced until they get bigger.
Venting is also hard when the fish is below the 4" mark. I have not been able to tell until mine grew to almost 4".