I have 6 males all are in 1 1/2 gal tanks.
Now here is something interesting. Two tanks are heated 78 degrees the other 4 are house temp. I had a veiltail that use to be in the heated tank and then moved him to an unheated tank. His tail is now back to normal, long and flowing, the one in the heated tank has just started this. They all have plants in their tanks (silk) and also have the company of each other and I do rotate them often as well. One thing I have started to use again is the Betta Spa which is the Almond Leaf Extract I put two drops of this into their tanks and I don't know if this is what helped heal the veil tails tail or what but its very interesting to see this.
On another note, I bought a new tank and it came with some colored rock for bettas, I rinsed the daylights out of it well and decided to put some into the two heated tanks only, this is the tank with the tail biter. Two days later is when I noticed his tail like this and he was dashing around the tank as well. Now this is the second time this has happened to me with colored rock for bettas I removed all the rock and now all the bettas are in bare bottom which is alot easier to keep clean and I will never add rock of any kind again to bettas. The other 4 at room temp did not have the rock and their fins are just gorgeous. So don't know if that can help others but I now believe that they use garbage color for aquarium rocks and obviously not good for fish either so bare bottom tanks it is and they really don't look bad at all.
I have just done another water change on this guy with water conditioner and betta spa and will see how he does, if it does not heal then he will go into an unheated tank and see how well he does there.