Q: I have two bettas in a minibow 2.5 w partition. Recently the Male betta has torn fins and the fins are getting more and more torn. He is on bettafix. Did the female do this to him?  

Question submitted by Grant, Dublin - OH

A: Hello Grant :). Not being able to see your betta makes it difficult for me to tell you for sure what is going on, but here are a few things to know or look into: 
bulletWhat kind of partition does your small tank have? Does it allow water to flow through? If so it should have small openings, such as holes or even slits. If the openings are too large, male bettas long fins may go through them as the betta rests against the partition. Another male on the other side may promptly proceed to chew on them (chomp chomp)
bulletHowever you mention "female", so I guess you have a female on the other side. Usually females do not go after fins in a partitioned environment. When in a spawning tank however, all bets are off :).

So that leaves me with two possible scenarios here:

bulletIf you have plastic plants, they may be the culprit. Some plants have sharp leaves and betta's fins will overtime get caught on them and start tearing. Select plastic plants with ROUND leaves that have no pointy ends or sharp edges.
bulletIf your male has long fins or is a halfmoon (with heavy finnage) it may have "blown" its fins. This is a common problem where the male's fins end up tearing because of over activity. I would assume that the presence of a sexy gal on the other side would cause such hyperactivity on his part LOL.
bulletIf this is a pet store betta, God knows heavy finnage is not going to be the problem here LOL. All of them are pretty much veil tails which are very narrow, and unless a veil tail has very long finnage, I don't see how it could "blow" a tail LOL. So your betta may have fin rot instead. 

My two cents: I would remove the female and place her in another tank/jar. This will have two benefits: The male should calm down, hence less chances of further tearing his fins and if it is a fin rot scenario, the female will not get infected (hopefully she has not yet). Next please check my disease page and see if the description of fin rot could apply to your betta. Since you are a novice, I would play it safe and treat him for it anyways. It is often hard for a beginner to tell blown fins from fin rot. Bettafix will not, in my opinion, be a suitable or effective treatment. Instead use the medications I listed in the fin rot section of disease page. To be safe, put female in some bettamax for a week or two. Prophylaxis. In time, when your male has fully recovered, you can put them back together, but this time keep an eye on them and if Mr. Betta is too overactive you might want to find two separate tanks for them permanently. Hope this helped you.