Please help me help my fish

Question
Hi,
I  am a first time fish owner. He was given to me as an anniversary present. Until a few weeks ago he and two cat fish (sucker cat fish, they are only little, sorry I'm prety useless when it comes to fish, i don't know what they are called) were the only ones in the tank. I have since added two small river fish, beleived to be perch. And they are small as well. I have only just realised (1/2 hour ago) that my fighting fish has lost alot of his tassels, nearly all of them. I knew something was different i just didn't realise what it was. I was told that they eat the Siamese pellets so that is all he has been fed since Febuary when i received him. There is always a water plant in there for him to eat. I also introduced a small air pump this time last week. is that ok? Every time i clean the tank i use the water alkaline purifier drops and replace the plant. I have just removed the new fish and air pump. What else should i do. Please help me i feel so terrible and horrible for not noticing earlier. I don't want him to die. And i think the water may be too cold. Any thing you could suggest to help would be great. And I'm not sure if this has any relevance but he has a couple of see through translucent spots on his remaining tassels.
Thank you so much! I can't wait to hear from you,
Yours greatfully,
Jamie

Answer
Hi Jamie,
You most likely have a Betta.  Here is some information on this beautiful fish:
Bettas should be kept in 5 gallon tanks, and there water should be around 80-82 degrees.  When bringing home a betta, we all know that the little sadistic cups they are kept in, are not heated, so we put the betta in unheated water, around the temperature he came in.  Then we heat his water slowly, very very slowly, ONE degree every day as bringing up their temperature too fast could cause death.  Adding a teaspoon of undiluted aquarium salt to his water helps with stress, and parasites.  (One teaspoon to five gallons of water)  In his habitat the betta may live in shallow waters, but he has lots of room to swim.  Small tanks, bowls, vases, and mirrored tanks are all money making machines, and not suited for the betta.  Vendors do not care, as long as they sell.  They are there to make a buck, and this is all that matters to them.  Bettas kept in small containers will get sick, and their lives are cut short.  They are intelligent little beings, and should not be treated this way.  Unfortunately, their are no laws to protect fish, and not much good information on how the betta should be kept.  In a five gallon tank, his water should be changed completely once a week, always using a good water conditioner such as "Stress Coat."  
Bettas should have varied diets.  Betta Pellets, Betta Flakes, Bloodworms, Glassworms, Plankton Flakes, brine shrimp, and one frozen pea a week.  One day you feed him pellets the next flakes, and so on.  He must be fed in small quantities 2-3 times a day.  Example:  2 pellets for one meal, or 2 flakes for one meal.  Their tummy is the size of his eye, and we must always remember this when feeding them.  One cooked frozen pea a week is a must.  Cook the pea, remove the outer layer, and cut it into tiny pieces.  Feed the pieces one at a time to your betta making sure he eats it, and that it doesn't fall to the bottom of the tank.  On the day you feed him the pea, feed him nothing else.  This is so he cleans out his system, and avoids Swim Bladder Disease.  The Betta is prone to this disease which begins with constipation, so it is better to avoid it.
The betta is a loner, and is better kept alone.  Never put two bettas, or one male, and female in the same tank.  The bettas are Siamese Fighting Fish, and he would kill the female, and any other male in the tank.
For now you must try to cure your betta.  Buy "Tetracycline" as soon as possible, and follow the directions on the package.
I hope this information helps, and if you have any other questions regarding your little friend please do not hesitate to write me.  I have bred bettas, love them, and know how attached we are to them.
Lynda