Demekin History
The Telescope Eye (Demekin in Japan) is one of the oldest fancy goldfish, dating back over 400 years. The eyes develop normally as fry but begin protruding around 6 months and reach full size by 2 years.
Variants include the all-black Black Moor, the orange-and-black Panda, the Dragoneye (Chinese variety with shorter eye stalks), and the Butterfly Telescope (fan-shaped tail).
Vision Problems
Despite the name, telescope-eyed goldfish have poor vision. The protruding eyes give them less acuity than normal goldfish, and they often miss food during feeding.
Compensate by feeding small pellets in the same spot every day so the fish learns where food appears, and by removing fast tank mates that out-compete them at meals.
Decor and Tank Hazards
Telescope eyes are fragile and tear easily on rough decor, sharp plastic plants, or jagged rocks. Use only smooth substrate (sand or pea gravel), silk plants, and rounded driftwood.
Filter intakes should be covered with sponge guards — strong suction can pull eyes against the intake.
Eye Injuries
Minor scrapes heal on their own with clean water. Severe tears (bleeding, white film, swelling) need treatment with aquarium salt (1 tsp/gallon) and methylene blue baths. In rare cases, the entire eye is lost — fish adapt and continue normal life with one eye.
Best Tank Mates
Other slow fancies: Oranda, Ranchu, Ryukin, Bubble Eye, Pearlscale. Avoid: Common goldfish, Comets, Shubunkins, danios, and any fast or fin-nipping fish. Better to keep a species-only tank.