Description

The term “Sea Hare” refers to a group of marine gastropods in the family Aplysiidae. They are essentially shell-less snails known for their soft bodies and two prominent rhinophores on their heads that resemble rabbit ears, hence the name. Several species are kept in marine aquariums, primarily for their algae-eating capabilities.

Here’s a general care guide for sea hares in a reef aquarium, keeping in mind that specific needs can vary slightly between species:

Tank Setup and Environment:

• Tank Size: A minimum of 50 gallons (190 liters) is recommended for smaller species. Larger species can grow quite large (up to 12 inches or more) and will require correspondingly larger tanks.
• Water Parameters: Maintain stable water conditions:
  • Temperature: 72-78F (22-26C)
  • Salinity: 1.023-1.025 specific gravity
  • pH: 8.1-8.4
  • Alkalinity: 8-12 dKH
  • Ammonia and nitrites should be 0 ppm, and nitrates ideally below 10 ppm.
• Water Flow: Moderate water flow is generally preferred to ensure proper oxygenation and nutrient distribution without dislodging the sea hare. Avoid strong, direct currents.
• Lighting: Moderate lighting is sufficient and helps support algae growth, their primary food source.
• Substrate and Rockwork: Provide ample live rock and a suitable substrate to mimic their natural habitat and offer grazing surfaces for algae. Shaded areas without direct lighting are appreciated. Ensure all filtration intakes are covered to prevent the sea hare from being sucked in.

Feeding and Nutrition:

• Diet: Sea hares are primarily herbivores, feeding on various types of algae, including hair algae, macroalgae, and cyanobacteria. Some species have preferences for specific types of algae (e.g., Aplysia juliana eats green sheet-like algae like Ulva, and the California Brown Sea Hare eats red, brown, and green algae as it matures).
• Supplementation: Ensure a steady supply of algae in the tank. If natural algae levels are insufficient, supplement their diet with nori (dried seaweed), spirulina, and other algae-based foods or commercial algae wafers. Parboiled lettuce can be offered if other algae sources are unavailable.
• Feeding Frequency: Feed daily, providing enough food to keep them healthy without overfeeding the tank. Monitor their grazing to ensure they have enough to eat.

Compatibility with Other Tank Inhabitants:

• Fish: Sea hares are generally peaceful and can coexist with a variety of reef-safe fish. Avoid housing them with aggressive or predatory fish (like triggers or larger puffers) that may harm them.
• Invertebrates: They are typically compatible with other reef-safe invertebrates like shrimp, snails, and non-aggressive crabs.
• Corals: Sea hares are generally reef-safe and will not harm corals. Their grazing habits can help control algae growth around corals.

Challenges and Considerations:

• Sensitivity to Water Quality: Sea hares are sensitive to changes in water quality and can be negatively affected by poor conditions or fluctuations in parameters.
• Feeding Needs: Ensuring they receive adequate nutrition can be challenging, especially in tanks with low natural algae levels. Consistent supplementation is necessary.
• Predation Risk: Small or juvenile sea hares may be at risk of predation from larger tank inhabitants. Provide ample hiding spaces.
• Defense Mechanisms: When threatened, sea hares can release a purple ink that can cloud the water. While not typically harmful in small amounts, it can affect water clarity and quality if released in large quantities. Ensure proper filtration with activated carbon to mitigate this. Some species can also release toxins when stressed or injured, which can be harmful to other tank inhabitants.
• Lifespan: Sea hares typically have a relatively short lifespan in the aquarium (1-3 years), and some species may have even shorter lifespans after laying eggs.
• Expert Care: Due to their specific needs and potential for releasing toxins, many sources recommend sea hares for expert-only aquarists.