sounds like a bacterial infection - and usually is a reflection of the water quality.

Do you use a filter and heater in this aquarium? Have you tested the water recently?

You can try doing a couple more water changes per week to help clear up the eye. It's something that is reversable.

This bacteria is called Ick. You can clear that up by using an antibiotic from your pet store. Should clear up in a few days. Dirty water makes ick move likely to develope.

Sorry Jm
It it is nothing like Ich at all if it was it requires more than a few day to cure.

Symptoms: Cloudy cornea, opaque lens, pop eye, swelling, blindness.

Cloudy cornea can result from a bacterial invasion. Antibiotics may help.
Opaqueness can result from poor nutrition or a metacercaria invasion (grubs). Try foods with added vitamins and changing the diet to include variety.
Pop eye (exophtalmia) can result from rough handling, gas embolism, tumors, bacterial infection, or vitamin A deficiency. Gas bubble or bacterial infection can be treated successfully with penicillin or amoxicillin.
Blindness can be caused by poor nutrition or excessive light. Lowering the light level and a change of diet to include lots of variety may help prevent it.

As you can see it is caused by polution of the tank water. This can be caused by insufficient % and water changes. Am I correct in thinking you are doing a 100% water change if so this has caused the mini Aqu to continuallly cycling.

Several questions.
water changes what % and how often?
Feeding amount and how often.
Filtration type, how often cleaned and how is it cleaned.
What are the water peramiters if you dont have a good test kit take a water sample to your local LFS and get a full test.

They will have suitable medications and only use as directed.

I also suggest you visit a site called Fishforums.com there is a special thread there fore Bettas.

Keithgh

Nice to hear from you again Grice. A fungus is among us. check out this link also. Just click eye fungus.

Here is a link that might be useful: Betta info

Hey Woeisme,long time huh?
Thanks to everyone who has tried to help.
Sky,I do have a heater and filter set up. I will take the water change frequency to heart.
Lm,I was pretty sure that it was not Ick. Thanks for the suggestion.
Keithgh,25% water changes weekly. I feed twice daily(except for Sat). I use betta pellets(can't think of the brand right now.It's late lol)Bio wheel along with filter cartridge. I clean filter housing,impeller,etc.. twice monthly.
Thanks again everbody(take it easy Woe).
grice

Okay - you don't clean the biowheel, right? That is where many of the good bacteria reside. Cleaning or rinsing this will rinse away or kill (with chlorined tap water) the resident bacteria.

Biowheels rarely get gunked up unless the filter hasn't been cleaned for a while.

I'd just increase water changes. If the eye is just filming over, then you caught it pretty early.

No,nothing like that. I don't touch the bio wheel.
Thanks.

Hey, guys, tighebettalover here again. Is it ok if I have two betta fish in a 2.5 gallon tank WITH A DIVIDER? our temperture is about 65 degrees at night in the winter and hotter in the summer. during the day in the winter is 68 and probably warmer in the winter. i don't want to get a heater from all the scary stories i've heard.....oh, btw, there is a light in the top. i'd appreciate some advice.

oops, made some mess ups on my follow-up..... when i said during the day the winter is 68 and probably warmer in the WINTER, the WINTER should say SUMMER. sorry!!!

Heaters can be deffective, a fully submersible one that has a thermostat is the best bet. Avoid the "mini" ones that are factory preset. Heaters are much better made these days and fewer incidents seem to happen. Between the 2 risks "overheating due to malfunction" or "no heat, and risk of disease" I'd take the malfuntion risk everytime. Another option is a Fish Room or move to Central to southern Florida.