The familiar transparent glass catfish is Kryptopterus vitreolus, a shy schooling fish from Thailand. It feeds in the water column rather than cleaning the bottom. Keep a group in a mature, calm aquarium where every fish can eat without competition.
Identify the species and keep a school
The aquarium trade long confused this fish with K. bicirrhis and K. minor. The species account at Seriously Fish explains the identification history. K. vitreolus reaches about 6.5 cm in standard length, not the 10–15 cm often repeated for “glass catfish.” Other species sold under similar names may grow larger.
Keep at least six, with more when the aquarium permits. A lone specimen is an unsuitable purchase. Group members often hover together in a sheltered part of the tank rather than constantly racing around.
A mature, shaded setup
Choose a tank at least 90 cm (36 inches) long; around 30 gallons is a practical starting size for a modest group, with additional space for companions. A long footprint provides more useful room than a narrow tower with the same volume.
Provide plants, shaded edges and an open midwater area. Water wisteria can add cover when suitable for the setup. Smooth furnishings and a secure lid help prevent injury or escape.
A useful aquarium range is 23–26°C (73–79°F), mildly acidic to neutral water and soft to moderately hard conditions. Fluval’s glass catfish care sheet stresses their sensitivity to changing water chemistry. Avoid chasing extreme wild-habitat pH values with repeated chemical additions.
Complete the aquarium cycle before stocking. Maintain zero ammonia and nitrite, monitor nitrate and perform regular water changes. Gentle to moderate circulation with surface movement is appropriate; a powerful pump aimed straight through their resting area is unnecessary.
Feed where they swim
Offer small foods suspended in the water, including suitable frozen Artemia, Daphnia and other appropriately sized aquatic foods. Introduce small pellets or fine flakes that the fish can actually take. Observe each fish feeding instead of assuming food on the substrate will be found later.
Shy arrivals may need quiet surroundings and patient feeding. Avoid repeatedly adding more food when they refuse it: check water quality, group security and food size, and remove waste. Glass catfish do not eat enough algae to function as algae control.
Companions and warning signs
Choose small, peaceful fish with matching conditions. Harlequin rasboras are worth assessing for a suitably sized setup; kuhli loaches occupy a different feeding area when both groups have enough space.
Avoid predators, fin nippers and boisterous fish that monopolize meals. A betta’s short list of supposed visual triggers does not predict compatibility: individuals vary, so any combination needs observation and a separation plan. Eggs and tiny fry may be eaten even by otherwise peaceful fish.
Persistent hiding, weight loss, rapid breathing or altered appearance deserves investigation. Quarantine arrivals in a suitable group and environment, and seek diagnosis before medicating. Home breeding is not routine; good long-term care is a more realistic aim than a promised spawning recipe.
