(i apologize in advance for not knowing a great deal about my betta.)
the betta we have is a school pet. we got him (at least i'm pretty sure it's a 'him') in january. i don't know what specific type he is, & i don't know how old he is. (he was 'rescued' from a high school science class - as far as i know they observed/compared changes in behaviour due to small living environment - but this may not be totally accurate).
he came to us in a flower vase (with only sea shells & one live plant), that i quickly exchanged into a 1 gallon plastic 'bug' container....complete with live lily pads, gravel, 2 plastic plants, & some colourful acrylic shells.
at first, he seemed pretty normal, as far as bettas go; he was swimming around, eating fine (i feed tetra bettamin once/day, about a fingernail full, with 2 fasting days over the weekends).
i change his water every 1-2 weeks - about 3/4 distilled water (as i was told to do), and the remaining quarter about 1/2 tap water (that has been sitting for 24 hours) & 1/2 old water. (& yes, i rinse the gravel, plastic plants, & shells well under warm water).
when i change his water, i 'catch' him using a cup (to reduce potential damage to fins).
occasionally he would build a bubble nest.
about 2 weeks ago i noticed he was staying close to the bottom of the tank & not eating. (i even noticed a film of food on the surface of the water).
after about 3 days of this i did a complete water change (again about 3/4 distilled water, & 1/4 tap).
within 24 hours he appeared to be back to normal.
now, about a week later, i noticed a pretty big bubble nest (even nesting above the water line), and even though he is eating, he is voraciously eating only a few flakes of food i provide, then leaving the rest........and he is VERY active (almost crazy-like).
[***his increase in this 'psychotic' activity level is what concerns me the most***]
he darts & swims almost constantly - like he is uncomfortable in his own scales (lol) - but especially when i go over to the tank. (he does not seem to be rubbing or intentionally bumping against anything). he flares a little when i show him a mirror, but mostly avoids it.
...and i also noticed - just today - that his tail fin seems to have been cut a little. it's a clean vertical cut, almost like someone took a pair of scissors to them (although this is impossible). it is only a very small 'snip' (for lack of a better word), as about 98% of his tail seems to still be there. (any chance he bit them himself?)
i realize i may have a perfectly fine, healthy fish (i've read that as long as there is a bubble nest, he is a happy fish), but i really just want to be sure.
(also, any advice on how i am caring for him, i.e., water, feeding, etc., would be greatly appreciated).
by the way, his name is 'peaches', as the kids in the classroom described him as "not as red as a strawberry would be, but more like a peach".
he is my first fish (ever) & i've already fallen in love with him, so i want to make sure i am doing right by him.
thanks for any help you can provide!!!!