It may be that he is in a larger tank now- some bettas have a harder time adjusting to larger tanks. Make sure the filter is on the low setting, or baffled.. HMs have a tendency to bite their own fins if they feel too heavy and dragging on them. So make sure he is the farthest from the filter if possible, he has lots of plants and a cave to escape into if he is feeling insecure in the larger tank, and if he is still insecure about having a neighbor.
He may just need a bit more time to adjust- for now just make sure to keep up on the water changes weekly, keeping the water at the right temp and a fair amount of medium and tall plants and he should calm down in time. Tail biting can be tricky, and sometimes with a regular routine and less stress they stop, but sometimes they won't. Think of it like a nervous habit- us biting our fingernails. So as long as there isn't a reason he would be biting his fins, then there isn't anything more you can do.
I have a boy who a week after I got him I fixed up his tank (new ones tend to get minimal at first for me to make sure they are healthy, I can watch their waste, etc).. and when I gave him gravel and added plants.. he freaked out and bit off most of his fins. I ended up taking it all out and gave him what he had prior and he stopped biting completely and his fins are now growing back nicely. So sometimes a change can be unsettling for them after they adjusted to one home. Give him time, and if it gets worse he may just need to either go back into his old home, or he will learn to adapt and in a longer amount of time relax.
Make sure there are no pointy or prickly plants, or rough decorations to cause shredding of the fins.
Fin rot you will be seeing black/red edges that are crusty looking and flaking off..
There is no medication to stop them from biting their own fins- it's a habit or a nervous reaction to something.
He may just need a bit more time to adjust- for now just make sure to keep up on the water changes weekly, keeping the water at the right temp and a fair amount of medium and tall plants and he should calm down in time. Tail biting can be tricky, and sometimes with a regular routine and less stress they stop, but sometimes they won't. Think of it like a nervous habit- us biting our fingernails. So as long as there isn't a reason he would be biting his fins, then there isn't anything more you can do.
I have a boy who a week after I got him I fixed up his tank (new ones tend to get minimal at first for me to make sure they are healthy, I can watch their waste, etc).. and when I gave him gravel and added plants.. he freaked out and bit off most of his fins. I ended up taking it all out and gave him what he had prior and he stopped biting completely and his fins are now growing back nicely. So sometimes a change can be unsettling for them after they adjusted to one home. Give him time, and if it gets worse he may just need to either go back into his old home, or he will learn to adapt and in a longer amount of time relax.
Make sure there are no pointy or prickly plants, or rough decorations to cause shredding of the fins.
Fin rot you will be seeing black/red edges that are crusty looking and flaking off..
There is no medication to stop them from biting their own fins- it's a habit or a nervous reaction to something.