The three most common causes are:
- Being carried in a net
- Being flown overseas resulting in hyperinflation of the airbladder, which can either break the back, or hyperinflate and deform the back LIKE scoliosis and…
- Lightning strike or electrocution
- You have to put nutrition on the list because specific nutritional deficiencies will cause widespread ‘broken back’ or scoliosis in Koi and goldfish at a very young age – usually noticed and avoided at the level of the breeder.
Less likely causes are organophosphate poisoning and Vitamin C deficiency
Scoliosis –> Broken Back —> Jerky Swimming = Electrocution
Fish with common scoliosis or traumatically-induced (net-carry) broken back will show up suddenly, but often it’ll be a week or two after the actual injury and here’s why: If you carry a fish in the net, it may ‘break it’s back’ or crack a vertebrae, or even luxate – subluxate a vertebrae which ‘kills’ the nerve to the muscles there. A fish muscle for swimming is organized in thick BANDS of muscle. You can see these “somites” in a fish filet on the counter at the meatstore. A broken back kills the nerves to one of these ‘somites’ and at first it’s limber. But the somite will ‘die back’ and become a smaller, contracted band of fiber – which ‘pinches’ the fish and screws up it’s fluid/graceful motion. “Broken back” is the symptom at that point.
What Can You Do about Broken Back or Scoliosis in Koi and Pond Fish?
Nothing. Make sure you ferret out any source of sudden, chronic or intermittent stray voltage – AND then feed these fish (which are often “sinkers” meaning they sink to the bottom as ‘negatively buoyant’ — with a decent sinking pellet. The best most-attractive I have found is: A Decent Hikari Sinking Pellet These are very small pellets which are best for almost any size fish which is infirm and needs enticement to eat.
“Usually shows up two weeks after the electrical discharge but in my mind, it was settled, the fish had been “hit” by stray voltage. From lightning or a surge through an adjacent appliance….
For a fish of her size, to have lesions like that, at that stage in life, there would only be two possible causes:
1. I’ve seen this in fish with scoliosis after a history of serious, bloodstream infections with Aeromonas / Pseudomonas – and I THEORIZE that these fish SOMETIMES get “microabscesses” in the spinal cord, *or* an Aeromonas osteomyelitis – of the spine – and so I’ve seen (as a postulated result) a rash of broken backs among an admittedly low percentage of fish (< 10%) I know to have bacterial infections. Another possibility is injections given too deep in the muscles of the back, may have done damage to the spine.
…or -VERY- possibly:
A lightning strike NEAR the pond can generate quite a jolt of electricity in the ground, and this dissipates RAPIDLY as the discharge goes into “ground” via heat, etc. But if close enough to the pond, and considering fish “jerk” in mere millivolts and milliamps – you can find these lightning strike discharges (of “gigajoules” my friend) reaching the pond in “still high enough” voltages to jerk the backs of some fish asunder – AND – folks are surprised to find, sometimes ONLY one or more fish affected (not all) which is mystifying – but common. The reasoning is purely “adjacency” to the discharge – the nearer fish with greater body power snapping their own spines more predictably than a fish further away and with less mass to snap the spine.”