Fancy goldfish breeds like bubble-eye and lionhead have been selectively bred to extremes that cause chronic health problems and welfare deficits.
Extreme goldfish breeds suffer from their selective breeding. Bubble-eye fish are constantly vulnerable to eye sac rupture causing painful infection. Lionhead and oranda goldfish with excessive head growth have impaired vision and crowded mouths. Swim bladder problems are endemic in round-bodied fancy breeds. These fish live with chronic physical limitations that reduce their quality of life. The breeding of animals to extremes that cause suffering is an inherent welfare problem regardless of the attractiveness of the result.