The Celebes Rainbowfish is an elegant Sulawesi species with iridescent colors and threadlike fins. A perfect choice for peaceful community tanks.
Overview
Telmatherina ladigesi is a small ray-finned fish from the family Melanotaeniidae, endemic to the island of Sulawesi (formerly Celebes), Indonesia. In the wild, it inhabits clear mountain streams and small rivers with moderate current near Makassar, where the water is highly transparent with a slightly alkaline reaction.
This fish reaches a size of 6-7 cm and has a slender, slightly laterally compressed body with distinctive threadlike extensions on the second dorsal and anal fins, earning it the occasional name "sunshine fish." The body coloration is olive-gold with a bright blue-turquoise longitudinal stripe running from head to tail. Males have more elongated fins colored lemon-yellow with black edging. Lifespan in an aquarium is 3-5 years with proper care.
Telmatherina ladigesi was first described in 1936 and quickly gained popularity among aquarists thanks to its unusual appearance and calm temperament. Today, this fish remains one of the most attractive rainbowfish representatives for smaller aquariums.
Tank Requirements
A school of 6-8 Celebes Rainbowfish requires an aquarium of at least 70 liters. Optimal water parameters are: temperature 24-28°C, pH 7.0-8.0, general hardness (GH) 8-15. These fish prefer slightly alkaline water of medium hardness, which favorably distinguishes them from most tropical species that require soft water.
The aquarium should be arranged with dense vegetation along the back and side walls, leaving the central area open for swimming. Vallisneria, Java moss, and hornwort work well. Floating plants will help create diffused lighting that highlights the iridescent coloration of the fish. A dark substrate is preferable, as rainbowfish look especially striking against it.
Filtration should be effective but without an excessively strong flow — an internal filter with adjustable output or a small canister filter will suffice. Moderate current is welcome, as these fish live in flowing waters in nature. Good aeration is essential, since rainbowfish are sensitive to low oxygen levels.
Feeding and Diet
Telmatherina ladigesi is an omnivorous fish with an inclination toward insectivory. In the wild, its diet consists mainly of small insects, their larvae, and zooplankton. In the aquarium, it readily accepts quality flakes and small pellets, but regular supplementation with live and frozen foods is necessary to maintain health and vibrant coloration.
Small bloodworms, daphnia, cyclops, brine shrimp, and glassworms are excellent choices. Live food is especially recommended during pre-spawning conditioning. It is important to note that rainbowfish have a relatively small mouth, so food should be appropriately sized.
Feed 2-3 times daily in small portions that the fish consume within 2-3 minutes. Overfeeding is dangerous not only for the fish's health but also for water quality. In my experience, alternating dry and live foods throughout the week yields the best results — the fish remain active and their coloration becomes more vivid.
Care and Maintenance
The Celebes Rainbowfish has a relatively low care difficulty level but requires stable conditions. Weekly water changes of 20-25% are mandatory to maintain water quality. Use dechlorinated water at the same temperature to avoid stressing the fish.
Regularly monitor water parameters using test kits — rainbowfish do not tolerate elevated nitrate and ammonia levels well. Timely filter cleaning and substrate vacuuming will help prevent organic waste accumulation. With good care, these fish rarely fall ill, but deteriorating conditions can make them susceptible to ich and bacterial infections.
Note that Telmatherina ladigesi is an active schooling fish best kept in a group of at least 6 individuals. In a school, the fish feel more confident, display natural behavior, and males show brighter coloration as they compete with one another.
Compatibility
The Celebes Rainbowfish is a peaceful species (aggression level 2 out of 5) that is well suited for community aquariums with other calm species. Excellent tankmates include other rainbowfish, such as the Boesemani rainbowfish or the dwarf neon rainbowfish, as well as peaceful tetras like the Congo tetra.
Among bottom-dwellers, panda corydoras and other small catfish that occupy the lower water layers are a great fit. Rasboras, such as the clown rasbora, also make a harmonious addition.
Avoid keeping them with large or aggressive cichlids that may damage the delicate threadlike fins of the rainbowfish. It is also not recommended to house them with very small shrimp — adult rainbowfish may treat juvenile shrimp as food.
Breeding
Breeding Telmatherina ladigesi at home is quite achievable with proper preparation. These fish are phytophilous egg-layers that deposit eggs on fine-leaved plants or artificial spawning substrates (spawning mops).
For spawning, prepare a separate aquarium of 20-30 liters with fine-leaved plants (Java moss is ideal) and a slightly elevated temperature of 26-28°C. Spawning is stimulated by generous live food feeding over the course of a week and a slight temperature increase. The female lays several eggs daily over several days, attaching them to plants with thin adhesive threads.
After spawning, the parents should be removed, as they may eat their own eggs. Incubation lasts 7-10 days depending on temperature. The newly hatched fry are very small, and for the first few days they should be fed infusoria or liquid fry food. After about a week, they can be transitioned to brine shrimp nauplii. Fry grow slowly and reach adult coloration at approximately 3-4 months.