Taxonomy & naming
Hippichthys heptagonus was described by Bleeker in 1849, with Indonesia as its type locality. It is a member of Syngnathidae, the pipefishes and seahorses, and is one of the species that enters freshwater. FishBase lists the common name belly pipefish.
Morphology
FishBase gives a maximum length of 6 in SL. Like other pipefishes it has a long, bony-ringed body and a small tubular mouth. The name heptagonus refers to the seven-angled body in cross-section.
Habitat
FishBase calls it common in the lower reaches of rivers and streams and in estuaries, including mangrove estuaries and tidal creeks. It lists the range as South Africa and Kenya to the Solomon Islands and some Philippine lakes. The water is fresh to brackish and the zone is tropical.
Feeding
FishBase records no diet for this species. Pipefishes take small crustaceans and similar tiny prey by suction.
Mating
The female deposits eggs on the ventral surface of the male's trunk or tail, according to FishBase.
Breeding
The male carries the eggs, which FishBase says are incubated for several weeks. The eggs sit in a brood pouch under the tail, and the male matures at 3 in SL.
In the aquarium
Pipefishes are specialist feeders that accept little besides live foods such as baby brine shrimp and small crustaceans. Keep it in a calm tank with no competitive tankmates, and expect to run brackish water. FishBase gives no temperature, pH or hardness for this species.
Conservation
The IUCN Red List lists Hippichthys heptagonus as Least Concern, assessed 1 June 2016.