Well for starters Mollies can get up to 4-8inches max inside your tank and I have had,Mollies and they got up to 7inches and were laying eggs like crazy so watch out for the breeding and hatching process when it does start to breed.As for the Black Mystery Snails you are looking at about what I've seen around 3-6inches possibly 8inches but,which is rare case though for that. Then for the Albino Catfish are you talking about the Albino Cory Catfish if you are then they won't get no bigger than around 2 1/2inches which is fine,if you are able to get around 3-7of them because they love to school and are great bottom feeders too
