New fish mom with 5 tanks overnight

Aug 2, 2017
hi, I am new at having my own fish tanks. My dad always had them when I was growing up, but now I have to do more than just "feed the fish"
It all started.......about 4 weeks ago when my silly teen daughter and her friends (gotta love 'em) brought home 3 feeder goldfish in a small plastic bag from pet store and left the bag in my kitchen sink!!!! What?!!!!! Apparently one of her friends , who was having a sleepover at our house was going to leave the 3 goldfish in the bag , a couple of days !!!! Unti she could bring them home to her "tank". Hmmmmm!! It was already 11pm when I discovered them, and I was furious at the irresponsibility. So off to the , thank goodness , 24 hour Walmart I went. I bought a 10 gallon (I know) way too small for 3 goldfish. Starter least I got them out of the bag in my kitchen sink. The 3 goldfish are doing amazingly well , coming from a feeder tank and only 29 cents each. They have been upgraded to a30 gallon tank ....still small but a work in only 4 weeks, I fell in love with fish keeping and I now have a 39 gallon bowfront , heavily planted live and fake with many mollies , platys , 3 albino corys ....oh sooo many fry.....who knew they would all live?! When the first batch of 30 was born , I put them in the first 10 gallon tank seems all 30 molly babies are still alive and growing... I need to find them homes because they keep coming! I stopped rescuing the fry from the main tank and there are over 50 fry of all varying ages in the original 39 gallon tNk , yes I'm being over run...
I bought a used 55 gallon with stand n filter from goodwill and have 2 angelfish, 5 black glow tetra, 4 Bruno's ares tetra and 6 white skirt tetra....all doing great ....except for one Bruno's ares ...
Anyway, last night bought a 15 column gallon aquaeon tank n stand ....when I got to house man said as he loaded my car "oh there's still a sucker fish and green barb in there.
HELP!! There was a 3rd he forgot to mention . It is a DANIO or what looks like one., but it's tail fin is almost gone. Not tagged or bloody ...just gone. It swims mostly at top and eats too. What should I do? Is it parasite? Or just nipped? Or shock? Any suggestions?