Complete Guide to Caring for Lined Seahorses (Hippocampus erectus)

The lined seahorse (Hippocampus erectus) is native to the Western Atlantic Ocean, ranging from the northern waters of Canada down through the Caribbean Sea. These captivating marine creatures inhabit coastal waters around coral reefs, piers, breakwaters, and dense aquatic vegetation like mangroves and seagrass beds.

Popular among marine aquarium enthusiasts, lined seahorses are often bred successfully in captivity. However, wild populations face threats from habitat degradation and exploitation for souvenirs and traditional medicine, leading to their vulnerable classification. To support conservation, it is essential that any lined seahorses kept domestically are sourced from reputable captive-bred stock rather than wild-caught individuals.

Keeping lined seahorses in a home aquarium is entirely feasible, but they require dedicated care, research, and commitment. Their slow swimming pace and delicate nature mean they should not share a tank with aggressive or fast-moving fish. A dedicated tank environment tailored to their needs is crucial for their wellbeing.

Appearance and Characteristics of the Lined Seahorse

Unlike typical fish, lined seahorses have a unique upright swimming posture and equine-like head, measuring up to about 6 inches (15 cm) in length. Instead of scales, their bodies are protected by bony plates arranged in ringed segments.

Their prehensile tails enable them to grasp objects such as plants or coral, which they often cling to rather than swim freely. Their body patterns can vary from distinct lines to dotted tails or saddle-like markings on their backs, contributing to their distinctive beauty.

Setting up a Suitable Home for Lined Seahorses

A minimum aquarium size of 150 litres is recommended when keeping pairs or a small group of lined seahorses. The tank should provide gentle water flow, stable saltwater conditions, and numerous hitching posts – such as macroalgae or soft corals – for the seahorses to grip and rest.

Maintaining the correct water parameters is vital: temperature should be between 22-25C (72-77F), specific gravity 1.020-1.025, and pH range 8.1 to 8.4. Regular water changes and high filtration quality, including a protein skimmer if possible, will help maintain clean water free from harmful pollutants such as ammonia.

It is best practice to keep lined seahorses in a species-only aquarium to avoid stress or predatory behaviour from other aquatic life, especially for first-time owners.

Feeding Your Lined Seahorses

Lined seahorses feed predominantly on live food, and feeding them can be a delicate task. Their staple diet consists of live mysid shrimp or baby brine shrimp. Culturing such live foods at home or purchasing them from specialist suppliers is often necessary, as seahorses may reject frozen or dried alternatives unless introduced at a very young age.

They require feeding multiple times daily, with food available for around 20-30 minutes per session before removing any uneaten food to preserve water quality. This feeding regime must be planned carefully, particularly if you have a busy schedule or plan to be away, to ensure the health of your seahorses is not compromised.

Seahorse Mating and Breeding

Lined seahorses are remarkable for their monogamous mating pairs, which bond for life and engage in daily courtship dances at dawn. They communicate using underwater sounds that intensify during courtship and breeding periods.

Uniquely, the male seahorse carries the fertilised eggs in a specialised brooding pouch located on his tail until the young are ready to be born. The female deposits the eggs into this pouch during mating. With the correct conditions and care, captive breeding is achievable and can be a fulfilling experience.

Health, Stress Signs, and Care Tips

Watch closely for signs of stress such as faded colours, laboured breathing, erratic swimming, or refusal to eat, which can indicate water quality issues or illness. Promptly stabilising water parameters, providing ample cover, and removing aggressive tank mates are key to recovery.

Quarantine any new seahorse arrivals in a separate tank with stable conditions before introducing them to your main display to prevent disease transmission.

Seahorses require gentle care and a well-maintained environment, but with dedication and knowledge, they can thrive as fascinating and delicate pets.

Responsible Ownership and Ethical Considerations

Always ensure you purchase or adopt lined seahorses from reputable captive breeders committed to sustainable practices, supporting conservation of wild populations. Avoid products or pets sourced from the wild to protect vulnerable ecosystems and animal welfare.

Seahorses offer a unique glimpse into marine life and deserve our care and respect through ethical and informed ownership.