tank gravel

Question
QUESTION: I just recently set up a new 1 gallon fresh water tank.  As part of the gravel I have used some plastic beads and some small sea shells.  Are any of those a no-no for fresh water tanks?

ANSWER: Hi Paula,
It all depends on what fish you are going to put in a one gallon tank.  Not too many fish will live long in a one gallon tank.  These tanks are sold, and should never be sold.  No fish is happy in these small tanks, but the vendor never tells you this, he is there to sell, and doesn't care.  It is better to invest in a bigger one, which doesn't cost too much more, and make sure your fish will be happy, and free of stress.  I just thought I would mention this to you.  Sea shells make the water alkaline.  Some fish cannot live in alkaline water.  If the plastic beads do not fade, then it would be okay.  Little bags of gravel would be the best to use.  I recently saw coloured glass rocks at the dollar store.  They looked nice, and they can be used in a tank.
I hope this helps.
Lynda

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

QUESTION: Hi Lynda,
I goofed.  My tank is a 10 gallon not a 1 gallon  and the fish I am interested in are Tetras, Sharks (I know that are not real sharks, Red Tails or perhaps Black Finned) and or maybe Bettas.  Thank you,  Paula

Answer
Hi Paula,
Sharks grow very big, and need big tanks, some need 100 gallon tanks, and above.  The Red Tail shark could live in a 10 gallon tank, but he would have to live alone.  Red Tail sharks get very aggressive as they get older, and can terrorize a tank.
You could keep a betta with cory catfish ( cory catfish must be in groups)neon tetras (kept in groups of 6)White cloud minnows, Otoclinus catfish, and platys.  I must mention here that sometimes not all fish get along.   Some bettas are more aggressive than others, and some are less, and get picked on.  There is no guarantee.  
Your tank must be cycled before adding fish.  This means that your ammonia level must be zero, nitrites zero, and nitrates should be low.  To cycle a tank buy a used sponge that fits your filter, and let the water run through it for three weeks, adding water that as evaporated.  Do not rinse the sponge, just squeeze out the access water, and put it directly into your filter.  A sponge is good for a very long time, until it is old, ragged, and falling apart.  When you need to clean your filter, do not rinse the sponge under tap water, rinse it in water that you have removed from your tank.  This way, you will always keep the good bacteria in your sponge.
Once your tank has the right chemistry, add two fish, wait one week, check your water chemistry, if it is safe, buy two more fish, wait another week, and so on.
Do 25% water changes every week, after the tank has cycled.
Hope this helps.
Lynda