platies and tiger barbs- a good community?

Question
QUESTION: sup karen,
i have 40 gallon tank. i just started...and i bought 8 tiger barbs,3 bala sharks and 3iridescent sharks .my buddy suggested to add some platies and mollies.... as the reproduce fast and fill my tank. i heard that the tiger barbs are fin nippers and i am confused whether to add the platies and mollies. please help me... one of my friends suggested that a big school of tiger babrs wont harm them... is it true..?if so, is this one of the steps to protect the other fishes.....? tell me the no. of fishes in this school....
thx, anush

ANSWER: Hi Anush,
Most likely the platies and Mollies will be fine. Your tiger barbs should be in a big enough group where they won't be interested in bothering other fish and instead they will be busy interacting with their own kind.
It's always good to keep a close watch on the new fish as you would do normally anyway.


Best wishes,
Karen~

---------- FOLLOW-UP ----------

QUESTION: hi karen, this is anush again. my buddy suggested that we should decorate my tank, so we thought about my tank like the ocean but we came across the problem whether we can put beach sand in my aquarium?will my freshwater fishes be okay?
thx, anush

Answer
Hi Anush,
The problem with beach sand collected from natural sources is it can be contaminated with pollutants and it will almost always have bits of shells and other materials that will dissolve slowly and cause your pH to rise. It should also be sterilized. But even there there can be leftover pollutants and its best to just go to your local petstore and buy regular sand (not marine aquarium sand) or go to your garden supply center and buy play sand. You'll have to wash it very well though and make sure as much of the dirt and dust is rinsed from it. But otherwise it makes a nice sand substrate. Silica sand is a larger grained sand you should definitely keep a lookout for. I use it in my aquariums and it is a very nice substrate. Easy to clean and isn't easily disturbed and doesn't create dust clouds like sand will when stirred up.

*Also keep in mind seashells should not be used in most freshwater tanks because most fish do not appreciate the increase in pH and hardness shells cause by them dissolving minerals into the water. However, African cichlids and Shell-dwellers. Shell-dwellers would be a fun little setup you could do if you don't have any fish yet. Their tank can be decorated like a beach. With a sandy bottom and shells for decoration as these fish hide inside seashells.

Best wishes!
Karen~