jw, what algae eater and cat fish, what type of mixed platy's, what type of other fish. This is very necessary.
If you want to keep more than 1 Dalmatian Molly, minimum recommend male to female ratio is 1:2 (M:F). You will be less likely to experience problem if you get even more females.
Suggestion: If you want to keep more than 1 Balloon Molly, minimum recommend male to female ratio is 1:2 (M:F). You will be less likely to experience problem if you get even more females.
Tiger Barb will likely to fin nip you're dalmatian molly, ballon molly and angel fish. Try increasing the number from 5-10.
At least 5 Tiger Barb are recommended in a group.
More information is a lot better. Also, they might be dying of stress due to these factors.