Betta tail problems

Question
Hi, my male betta has been biting/eating his own tail! I noticed this today when i went to change his water. His tail is obviously smalled than yesterday and it looked like it was torn. His tail used to be this size: ----------------- . Now it is ------- . I'm worried that he might eat all his tail and start eating his own scales! I think he ate his tail because i can't find the any tail parts in his tank. He lives in a 2 gallon unheated tank and no filter. I change his water two to three times a week and treating the water with bettaplus bowl treatment which makes the water safe. He has been doing fine ever since. I don't put any plastic plants or gravel because i heard the plants might tear his tail and bacteria may grow on gravel and make it harmful. I feed him once a day using hikari betta bio gold. I uually give him 2 pellets. Am i feeding to little or is he sick? WHat can i do to stop him from eating his own tail?

Answer
Hi Jen,
Bettas usually bite their tail if they are stressed.  He should have a silk plant that you can buy at your pet store for a small sum, and some litte toy that he can go through.  Is your PH too high?  Betta like neutral water, or somewhere near it.  6.5 -7.0  Is there too much light in your tank?  Betta prefer the light of day, and lights, lamps could stress him.  How long have you had your Betta?  Bettas are shipped to the pet store in small bags, sometimes only enough to cover them with little water.  In these small bags, some bettas curl, and are so stressed, they bite their tails, and fins.  Then they are put into these horrible little cups, which does not help their situation.  Is your water heated?  The betta is a tropical fish, and should be in heated water.  His water should be 80-82 degrees.  Under this temperature, the betta is cold.  If he isn't in a heated tank, please consider buying a thermostat.  Bring the temperature up very very slowly.  Bring it up one degree every two days, as bringing the temperature up too quickly would cause death.  The same goes if his water temperature is fluctuating.  One degree drop in temperature is enough to stress a fish if this happens everyday.  Temperature that fluctuates, is deadly for all fish.  
Bettas should be fed 2-3 times a day in small amounts.  You don't want to starve him.  Two pellets, or two flakes for one meal is enough.  He should also have one cooked frozen pea a week, with the outer layer removed, cut into tiny pieces, and fed to your betta one piece at a time.  On the day you feed him the pea, feed him nothing else, till the next day.  This is important.  The betta must have one pea a week to prevent Swim Bladder Disease which is caused by constipation which often goes unnoticed.  Daphnia should also be part of his diet.  Vary his diet so that he gets all the vitamins he needs.  Betta Flakes, Plankton flakes, brine shrimp, mealworms, glassworms, bloodworms should be part of his diet.  One day feed him pellets, the next bloodworms, the next flakes, and so on.
For now, add 1/2 teaspoon of diluted aquarium salt to his water.  Buy Bettafix, and follow the instructions.  If his condition worsens, please write back to me.  Keep his water extremely clean.  I hope we will find the solution.
Lynda