Fin problems w/ Betta!!

Question
I recently "adopted" two male betas... my mom found them in their sale cups in the parking lot of a local mall, and I set them up with one of the separated tanks to chill out in.  They've been doing fine, looking healthy and all that as far as I know, until just recently.  One of them (Derty) turned up with in just the last day or two with some fin problems.  it looks like they're splitting, and there's a rather large section of fin on the bottom of the tank... kinda made me cringe...  I clean the tank out at LEAST once a week, give them a fixative for the water at that time and feed them some color enhancing food.  I've looked on this site and it doesn't necessarily sound like age (it's not curling, and it's actually sloughed) or tail rot (doesn't appear to be necrotic around the site where it detached...)  and i'm not noticing any changes in the other fish whatsoever.... so.... could you tell me what I can do for them?  What I'm doing wrong or what I could change?  I don't know much about them at all, and it kills me that he's sick! Also- on a side note- I've read on this site that bubbles at the top of the tank with too many fish means an excess in ammonia- would this apply to my TWO beta tank with TWO betas in it?  thanks, and sorry for being so ignorant about these guys!!!!

Answer
Dear Jennifer,

You are not being ignorant; the fact that you are going to so much trouble to help these fish proves you are very worthy to care for them.

The second part of your message, sorry, but it made me laugh. A group of bubbles at the top of the tank is called a bubblenest and it is a sign that your betta is happy, healthy and willing to breed. Of course, you do not have to breed him but it means he is healthy. In breeding, the male deposites the fertilised eggs in this nest. It is a good sign!

But on a more serious note - Derty's mysteriously dissapearing tail! You say it is falling off in chunks, so it is not being devoured by bacteria (fin rot). You also say it is not necrotic or rotting, which further eliminates any kind of disease.

I am led to the conclusion that the fish has in fact bitten his tail - it's not uncommon, my Jeremiah did it only a few weeks ago. It can be brought on by a sudden stress, like being left in a car park! (By the way, your mom did a good thing!)

Keep his water clean and warm, add some aquarium salt which is available from most pet/aquarium stores. Do not use table salt, it can kill! Derty's tail should heal up fine.

Hope he recovers quickly!

Prue