Hello candyflossgirl and welcomeYour tank is approx. 80% full when the fish are adults.My only question is what filter do you have?This will determine if you have enough filtration to add a few extra small fish.Hope it helpsStephen
Currently I'm using the filter that came with the tank. It's a love fish 64L panorama tank. Am going to upgrade to the fluvl u2 though
How hard is your water? If your water is hard go for a couple of mollies maybe platys, if your water is soft, go for tetras.