catfish with bent spine

[idonno]

My Rendahls catfish has a s shaped bend in his tail. I noticed it yesterday after i put new plants in the tank. I've had him for 2.5 years so maybe age? But i have no idea how long they live for. He's still swimming, eating and behaving normally. He's a bit skinny compared to my other rendahl but has always been lean. All other fish are fine except my platy just died last week... I'm worryed about fish tb coz i only noticed after i had my hands in there and i have cuts on my hands and i dont want him to die. Nitrites: 0 ammonia: closer to .25- could that cause it? Tank is 180L, has been set up for 1.5 years

[Silurus]

Spinal scoliosis/lordosis in fishes has been associated with inbreeding, nutritional deficiencies, and low oxygen levels. There is no known cure.