My tank mates

Question
Hello,
 I have a few questions but let me tell you a little bit about why i have the tank i have now. I am new at having fish for pets but i easily fell in love with them. When i  started i was misdirected several times and i decided i was better off to look up info on the Internet and find out for myself rather than ask the local pet store that new nothing about what they were selling. I was told for my first tank that the fish i liked would all go together in a tank till i did research(because i noticed behavior in some of the fish and i was concerned). I started out with 1 angelfish,2 tetras,1 iridescent shark, 1 tiger barb. well the tiger barb nipped everyone fins and was just mean so i went back and they sent me home with 2 more. Well so i did research and i found out tiger barbs are aggressive and are fin nippers and angelfish eat tetras when full grown(mine is growing fast but she is very nice and even feeds right out of my hand),tiger barbs are best in groups of 5 or more,he told me the shark stayed at inches and it gets up to 1to3ft plus that night it was already sick with ick so he was ill when i bought him so i treated him and he died i took the tiger barbs back. Now in my tank i have my beautiful angelfish, 2 tetras, 3 Mollies, and i just added a red tailed shark and a rainbow shark which i was told would only get to 4in but also again found out different. So i like all my fish and they all get along besides the red tailed shark is always going after the Mollies,tetras,and rainbow(the most) and the rainbow hides from him and she wont eat because she is scared. so here are my questions for you. Should i take the red tailed shark back? or should i just take them both back? do you think with my angelfish not bothering the tetras at all and such a calm, nice fish that she will eat them? Oh and the dalmatian molly is a male and he other two are females when i added them they all started playing and now stay in a group of 3 but its funny because he gets near and softly rubs up under on the female and then starts what looks like a dance in the water....what is he doing? Thank you so much for you time and  i am so sorry about being long winded i just wanted you to have a little history on the tank mates.

Answer
Hi Ashleigh,
It's really a shame that petstores can never ever give the proper advice and it results in fish being sold to unwary people and loads of problems down the road from then on.

The problem with the red-tailed shark is common. These fish, while very pretty tend to want to defend a territory and have the habit of chasing and nipping other fish in their aggression. They really would only do well as the only shark in a decent sized tank where they can establish a territory such as a 55gallon. The red-tail shark will also fight the rainbow shark constantly as well.

I'm not sure how big your tank is. If its at least a 30 gallon you might be able to keep one of the sharks. (likely the rainbow). But as you have seen, the red-tail is just too bossy and territorial. Its possible your Rainbow shark may take over then and try to hold a big territory too.

Its kinda up to you whether or not you want to chance the rainbow shark. Each fish tends to be somewhat an individual in their personality.

As for the Angelfish, I keep my angels with small fish like Zebra danios, lemon tetras, ext... All the time. I even have a 3 inch long (not including tail) angelfish with a neon tetra and neither fish bothers the other. I think tetras and angels can definitely be kept together if they are raised together from a young age.

As for the mollies. The male is "courting" the females in a pre-mating ritual. Very common with livebearers and males have a very strong instinct to breed constantly.

Best of luck and I hope this helps!!
Karen~