FIN DAMAGE

Fin damage may be the most common issue that fishkeepers will encounter with these fish. Domesticated betta splendens owe their massive, flowing fins to selective breeding by humans. Their wild counterparts - also betta splendens - have very short fins, like the "plakat" variety of bettas sold in pet stores.

 

The long fins that bettas have been bred for serve no purpose beyond their appearance. As bettas are naturally quick swimmers (see our BETTA MYTHS page - these aren't lazy, bottom-dwelling fish!), with their torpedo shaped bodies and incredible jumping ability in the pursuit of food, these glorious fins are often a hindrance, encountering great amounts of resistance as they swim or encounter currents, like huge billowing sails, or the parachute deployed behind a dragster.

 

Since this part of their anatomy works in opposition to their behavior and nature, stress and injuries to the fins are common.

Different Types of Fin Damage

In my experience, there are three main forms of fin problems experienced by betttas, and these three are outlined below.

 

The table below summarizes the general distinctions that I see between each issue - please read on below for more details and pictures of each problem.

MECHANICAL DAMAGE
TAIL BITING
INFECTION/DISEASE
  • Long tears along the fin length, parallel to the rays
  • May be a single tear, or many
  • Long tears along fin length
  • Large chunks of missing fin
  • "Tattered" fin ends with protruding rays
  • Areas of damage may be quite large
  • Discoloration at fin edges
    • Possibly blackening or darkening
  • Fuzzy or slimy patches/visible infection on fin
  • Fin seems to be disintegrating (both rays AND webbing in between are degrading)

Mechanical Damage

CAUSES

  • Water resistance/strain on the fins caused by:
    • Strong currents in the tank
    • Powerful swimming by the fish (this is a good thing in the long run!)
  • Physical injuries caused by:
    • Snagging, abrading, cutting or tangling fins in tank decor/equipment
    • Fins that have been sucked into an uncovered filter intake
SYMPTOMS:
  • Long rips up the length of the fin, parallel with the rays
  • Long strips of fin tissue/rays remain in between rips
  • Appears suddenly/dramatically
  • Possible bloodied ends/edges
  • No signs of disease/infection
TREATMENT:
  • Small partial water change (10-20%), making sure to remove all uneaten food/debris that is visible
  • Test water more frequently, making sure to maintain perfect water quality
  • Monitor fish for any signs of infection
  • Allow fish to heal injury on his/her own

Tail Biting - a special kind of mechanical damage

Naughty Turlington the tail-biter
Naughty Turlington the tail-biter

Yes, bettas quite often turn on themselves and attack their own tails! While I don't know the reason with absolute certainty, I have a few suspicions.

 

POSSIBLE CAUSES:

 

  • Anxiety over viewing their reflection in a tank wall
    • Often the way a tank is positioned relative the light sources outside of it, etc., will allow a betta to see their reflection in one of the tank walls
    • This can lead to hours of angry, flaring betta behavior that is unresolved
  • Fear over a tank that does not provide enough hiding places, etc.
SYMPTOMS:
  • Long rips up the length of the fin, parallel with the rays WITH
    • large chunks of fin tissue missing altogether
  • Long strips of fin tissue/rays may remain in between rips
  • You may catch your fish doing the biting!
    • My biters would often spin in awkward, sideways circles until their tail fin was almost draped over their face before attacking
  • Appears suddenly/dramatically
    • You may notice additional chunks go missing from the fins after the initial damage, as the fish bites repeatedly.
    • However, if you notice fins continually degrading, you must be sure to rule out disease, as infections may also cause very rapid finloss - biting should not be diagnosed until disease has been ruled out.
  • Possible bloodied ends/edges
  • No signs of disease/infection
Turlington's repeated fin biting
Turlington's repeated fin biting

You can see the progressive damage done by multiple instances of biting. This damage appeared within the span of a day or two.

 

This fish was in a securely divided tank with another betta visible to him on the other side of the tank. He spent a lot of time flaring and displaying to this other betta, and I suspected that this was stressing/agitating him and causing the biting. Moving him to his own tank, out of view of other fish stopped the biting.

TREATMENT:
  • Evaluate and remove any environmental stressors, such as:
    • The fish's own reflection visible in walls of the aquarium
      • Place a leafy aquarium plant in front of the wall that is reflecting
      • Change the lighting to reduce reflections
    • Make sure that the fish is not in view of other fish, especially other bettas
    • Add more plants/hiding places to the tank
  • Small partial water change (10-20%), making sure to remove all uneaten food/debris that is visible
  • Test water more frequently, making sure to maintain perfect water quality
  • Monitor fish for any signs of infection
  • Allow fish to heal injury on his/her own

Infection/Disease