I agree that an established filter is by far the best thing to use to speed up a cycle. I haven't had much luck with decor and gravel helping for some reason. One time in an emergency I filled a 5
gal with water from my primary tank and added a betta right away. I wasn't able to move anything else over to the new tank..just the water. I tested the water daily and it never went through a cycle...for a couple days there was .25 or less of ammonia but that's it...never any nitrite. I was impressed..didn't think it would work quite that well.. but it did. As for the bettafix I started to worry a bit about it because on another forum people were saying not to use it..but..I've used it according to the bottle directions a few times for shredded fins and the betta has healed quickly and never shown any side affects or discomfort..the main ingredient is melaleuca which is a variety of tea tree which I have read is very beneficial in healing wounds and tears on bettas. I'm really not sure if it's the best thing to use or not but I've had great success with it