When it comes to captive care, damselfish (family Pomacentridae) certainly have a lot going for them. Many are chromatically blessed, many are more diminutive is size and most are very hardy. The problem: many can become very quarrelsome. Thus, you have to choose which damselfish you purchase or consider very carefully when choosing its tankmates. There are a number of bright blue damselfish available to aquarists that are sold as “neon damselfish” that are less combative than many members of the pomacentrid clan. One of the many beautiful members of this family that is encountered by aquarists is the neon damselfish (Pomacentrus coelestis).
Difficulty: The neon damselfish is an ideal aquarium inhabitant. It is very colorful, doesn’t get very large and is very durable. The neon damselfish will readily acclimate to its new home and will eat most aquarium fish foods. Feed it every other day in a reef aquarium or once a day in a more sterile fish-only system. Foods of choice include frozen preparations for marine herbivores, frozen fish eggs, frozen Cyclops and even flake foods.
Physical description: The neon damselfish is bright blue with a yellow anal and caudal fin. The similar goldbelly damselfish (P. auriventris) has a yellow belly, tail, anal fin, pelvic fins and rear portion of the dorsal fin. The similar P. alleni (Allen’s or blue star damselfish) has yellow only on the anal fin and a black area on the lower portion of the caudal fin. These two species are fairly similar in husbandry requirements to P. coelestis (P. alleni may be a little more docile than the other two and bit less hardy). Pomacentrus coelestis reaches a length of 3 inches.
Range: The neon damselfish is found from the eastern Indian and western Pacific oceans (most found in the aquarium trade are collected from Indonesia). Pomacentrus coelestis inhabits shallow, inshore reefs (usually in less than 30 feet of water) and is often found in microhabitats exposed to surge. Neon damselfish are often found in loose groups. Like most members of the genus Pomacentrus, P. coelestis is omnivorous. The neon damselfish feeds on diatoms, detritus and associated microinvertebrates. It will also consume plankton.
Compatibility: Damsels are renowned for their surly dispositions. But P. coelestis would have to be considered one of the mellowest of the pomacentrid clan. Not that it is above chastising new, peace-loving fish added to a smaller aquarium it happens to be in. But in a moderate to large-sized aquarium the neon damselfish typically behaves itself.
The most likely targets of the neon damselfish are small bottom-oriented species, such as dartfish, firefish, gobies, wormfish, small wrasses and dragonets. In larger aquariums (135 gallons or more), they can be kept in small groups. If you get two male neon damselfish, they will need to have enough room to set-up their own territories or, if room is lacking, you may have to remove one or more of these fish if they fight constantly. In many cases, adding a larger group (say five individuals) of P. coelestis is better because that will disperse aggressive interactions between more individuals. The neon damselfish is likely to be challenged and dominated by damsels of the following genera: Dascyllus, Microspathodon, Neoglyphidodon, Plectroglyphidodon and Stegastes. Large anemonefish and even some Chrysiptera spp. have also been known to punish P. auriventris as well, including the Fiji blue devil (Chrysiptera taupou) and the onespot damselfish (C. unimaculatus). Its small size means that P. coelestis is suitable prey for a larger number of piscivores.
Aquarium conditions: Neon damselfish can be kept in aquariums as small as 20-gallons, but aquarists must be aware that in such small confines P. coelestis is likely to be more aggressive to smaller passive species. Provide it with plenty of hiding places.
Keep the water parameters for the neon damselfish as follows: pH of 8.1 to 8.4, specific gravity of 1.019 to 1.025 and a water temperature of 74 to 82 degrees Fahrenheit.
Breeding: The neon damselfish species will spawn in the home aquarium; females lay their eggs in crevices or in shells. The males guard the neon damselfish eggs from potential predators.