bump on my beta

Question
Hello, I am worried about my son's beta fish, I got it for him for Christmas on 2007, so he has lived with us more than 1 year. About 2 months ago we noticed this protruding bump, right behind his left side fin, he has not shown any difference in activity or personality, he continues to be very active and eats the same. We have had him in the same environment since we had him home , he lives in a 6 inch long , and 4 inch tall by 3 inch deep, tank. We feed him beta baby pellet (Hikari Betta Bio-Gold), 4 pellets every other day , and he is so active and aggressive , that he jumps up and out of his water every time we open his tank to feed him, (he is so funny).
We only treat his regular faucet water with "splendid Beta" complete water conditioner, according to directions.
His tank is in our kitchen counter , witch is the most tepid weather area in our apartment.
I hope that is enough info , and that hopefully you can tell us he still has some years to go , we love "Splashy" very much.
p.s let me know if a picture would help.

thank you so much
Paula

Answer
Hello,
A bump or lump is very hard to diagnose.  It could be a tumor.  Most tumors aren't cancerous, and fish may live long, and healthy lives with them.
Here is some information on Bettas that maybe would interest you:

Bettas need 5 gallons of water or more to be healthy, and happy.
In their habitat the betta may live in shallow waters, but they have lots of room to swim.  
Keeping Bettas in small bowls, containers, vases etc, is cruel.  The Betta is one of the most mistreated fish on the market.
They need a heated tank.  Temperature should be 78-80-82 degrees.  They are tropical fish, and are cold under this temperature.  Cold bettas get sick, are miserable, and live unhappy lives. ( Always remember  when heating a tank, do this very very slowly..1 (one) degree every two days, as bringing up the temperature too fast would kill your Betta.)  The temperature should always be stable.  Fluctuating temperature is very bad for bettas, and any other fish.  
They should have a silk plant in their tanks, so that they can rest on the leaves  They also need a little tunnel or some knick knack that they can go through.   One teaspoon to five gallons of diluted aquarium salt may be added to his water, when a Betta is well.  
Aquarium salt helps them with stress, and helps with parasites.  However if a Betta is showing signs of a swollen tummy, salt should not be used.
They need a varied diet. This is very important.  Betta pellets one day, Betta Flakes the next, Daphnia the next, and bloodworms should be given once a week as a treat.
He should be given one well cooked frozen cooked pea a week, and on the day you give him the pea, he should fast.    
A betta is prone to constipation, and constipation leads to Swim Bladder Disease.  A frozen cooked pea a week keeps them from getting constipated.  Always remove the outer layer of the pea, and cut it into small pieces feeding it to your betta one piece at a time.
They should have 2-3 small meals a day, and not one big meal.  We must remember that their tummy is the size of their eye.
Example:  2 pellets for one meal.
Water changes are very important.  Water changes must be made every week without fail with a good water conditioner such as Aqua Safe or Stress Coat.  There is also a conditioner made especially for bettas.  If you do not have a filter, change all the water in his tank weekly.
When treated well, a betta can live up to 8 years, if you buy him when he is very young.  (Unfortunately we do not know their age when we buy them at the Pet Store which is why some bettas die two or three years after we have bought them.)
He's an intelligent little fish, and should be treated with kindness.
Too many vendors know nothing about the betta, and don't care...so don't give good information on how to keep them.
They are there to sell, and will say anything just to make a buck.  They send you home with your bought betta, telling you a small bowl is perfect, and bloodworms!  The poor customer thinks he has everything he/she needs, and then the fish gets sick, money is spent to cure him, and eventually the fish dies.   
This turns my stomach over.  Unfortunately there are no laws to protect fish.  
Bettas kept in small bowls, one gallon tanks, and vases, will get sick, and are very hard to cure in such little water.  They end up dying, and
that hurts the person who has grown so attached to them.  They don't deserve to be treated this way.
This is how a Betta should be treated.  If treated this way, you will have your friend for a long long time.  I have bred them, love them, and know what is good for them.
I hope this helps you understand the Betta a little more.
If his condition changes, and he stops eating, or his tummy is swollen, please write back to me, as he could have something else...but a betta who eats is a good sign.  (His tummy is located just below his chin)
I hope it is nothing serious.
Lynda