A “blow-out” is a term betta breeders and hobbyists use to describe a small hole or tear in the fin tissue caused by spreading or “flaring” of the fins. Torn or frayed fins can be caused by a number of things including , injury from tank décor, biting from other fish or even from a . The term blow-out is not used when holes or tearing are the result of anything other than tension in the tissue caused by flaring.
More information regarding your tank and fish would be very helpful
I'm hoping you can help my betta fish Phelps. I have had him for about 3 months now, he is normally very active and outgoing. However, for the past couple of days he has been very lethargic but this morning I noticed he was looking REALLY bad, his tail is frayed and he is only using one of his little side fins (I don't know what the proper name is.)
Why Are My Betta's Fins Becoming Ragged? | My Aquarium Club
Also ensure they have an enriched environment, this means interesting things to explore, and mix it up regularly with plants, rocks, ornaments, ceramic tubes, floating ping pong balls, moss balls, and other smooth objects (no clay flower pots with sharp edges/chips that can snag fragile fins). Nourishing your fish’s mind is just as important to his long term health as nourishing species specific food (never generic aquarium fish food to bettas, only food meant just for them).
My betta fish has been experiencing a rapid deterioration of his fins
Next, assuming your Betta or other fish (such as an Oscar or Arowana) actually has a bacterial infection you may have to start . The most common bacterial causes of fin rot being Columnaris & to a lesser extent .
Pseudomonas bacterium may be the cause of mild fin rot infections in which the fish generally only display frayed fins and black fin edges.