Lined Seahorse (Hippocampus erectus) Breeding Guide

Breeding the lined seahorse (Hippocampus erectus): male pouch pregnancy, ~20-21 day gestation, large broods, and the challenge of rearing partly pelagic fry.

Overview

Hippocampus erectus reaches about 17.8 cm and ranges through the Western Atlantic from Canada to Brazil, including the Gulf of Mexico and West Indies, where it associates with gorgonians, seagrasses and floating Sargassum (FishBase). It is one of the more commonly captive-bred seahorses. The species is ovoviviparous, with eggs developing in a brood pouch beneath the male's tail (FishBase). IUCN status is Vulnerable, and the species is listed on CITES Appendix II (FishBase, Wikipedia).

Sexing

Males are identified by the brood pouch under the tail and develop it at about 5-7 months of age; females lack the pouch (Wikipedia). Fish reach full size by roughly 8-10 months (Wikipedia).

Conditioning

The lined seahorse is a slow feeder easily outcompeted by faster tankmates, so it is conditioned in a calm species-only tank with gentle flow and frequent feeding of suitable frozen and live foods. Stable parameters in the reported range support reproduction.

Breeding Setup

A species-only aquarium with low flow and abundant hitching structure such as gorgonians or macroalgae suits a pair or small group. Pairs bond and the male's pouch maintains oxygen via a capillary system and regulates internal sodium and calcium levels during pregnancy (Wikipedia).

Spawning Behavior & Trigger

Pairs are reported to be monogamous, choosing partners they continue to mate with, and perform daily ritual dances and produce clicking sounds by moving the coronet against the skull to maintain their bond (Wikipedia). During transfer the female deposits her eggs into the male's pouch, where they are fertilized and incubated.

Egg & Fry Care

Females can produce 97 to 1,552 eggs, and a single male can carry up to about 650 at once; FishBase cites fecundity of roughly 1,552 young per event (Wikipedia, FishBase). Gestation lasts 20-21 days, varying with temperature, after which the male anchors his tail and arches rhythmically to release the young (Wikipedia, FishBase). Newborns are about 11 mm and tend to swim near the surface after birth; survival is low, reported at only about two juveniles per hundreds hatched (Wikipedia). The partly pelagic, surface-associated fry are more difficult to rear than the benthic young of the dwarf seahorse.

Common Challenges

The large brood, low natural survival, and surface-swimming fry make rearing demanding: gentle flow, a steady supply of small live foods, and careful nursery management are needed. Slow adult feeding also requires that seahorses not be housed with fast competitors.