In one of the tiny tanks at work, I have a betta in with 2 white clouds. They've been together about 2 mos(?), maybe 3. One of the white clouds has a mildly shredded tail fin today, and a shred from one of his gills or his throat area (I can't really tell). The tank is unheated/unlit, stays in the low-mid 70s. 2 small plants. Is it more likely that the betta is harrassing the white cloud or that he has a disease? No new fish/plants have been added recently. Any thoughts/advice would be appreciated.