Nudibranch and Sea Slug Aquarium Guide: Advanced Only
Almost every nudibranch sold in the marine trade dies within weeks, not because the hobbyist did anything obviously wrong, but because the animal was an obligate specialist on a prey species that was never in the tank. This nudibranch sea slug aquarium guide from Gensou Aquascaping in Singapore explains the prey-specificity problem, which species can actually be kept with realistic effort, and why the rest should be left in the ocean or in specialist facilities. If you want colour and movement with better survival odds, buy a shrimp.
Quick Facts
- Number of described nudibranch species: 3000+, most are specialist feeders
- Species viable in home tanks: under 10, realistically 3-4
- Typical survival in unresearched purchases: 2-8 weeks
- Berghia nudibranch diet: aiptasia anemones only
- Lettuce slug diet: Bryopsis and other green algae — not technically a nudibranch
- Temperature: 24-26 °C for most tropical species
- Salinity: 1.025, stable
The Prey Specificity Problem
Nudibranchs evolved as specialist predators on specific sponges, hydroids, bryozoans, anemones, or other nudibranchs. A spanish dancer eats particular sponges; a chromodorid eats particular sponge species; an aeolid eats specific cnidarians. Take a colourful wild-caught nudibranch home and put it in a tank without its prey and it does not eat substitutes — it simply shrinks and dies over weeks. The aquarium shop cannot tell you what it ate, because in most cases nobody knows.
This alone disqualifies the majority of species seen for sale. When in doubt, assume it will starve.
Species Worth Attempting
Berghia (Berghia stephanieae) is the standout. Its diet is well understood — aiptasia anemones — and its role is genuinely useful in reef tanks with pest infestations. A group of 6-10 berghias will eliminate a moderate aiptasia problem in two to three months. They are captive-bred in several regional facilities and appear on Carousell at $8-15 each.
Lettuce sea slugs (Elysia crispata) are technically sacoglossans, not nudibranchs, but they are sold under the umbrella. They graze Bryopsis and sequester chloroplasts from the algae they eat. They last longer in home tanks than true nudibranchs but still decline when their algae source depletes.
Blue dragon sea slugs (Glaucus) and the various pelagic aeolids are not viable. Spanish dancers, chromodorids, and most brightly-coloured reef nudibranchs are functionally impossible without a research-scale sponge culture.
Berghia Deployment
Add berghias to a reef tank with known aiptasia at least 2 hours after lights out. They are nocturnal grazers and acclimate better in darkness. Drip acclimate over 90 minutes to match salinity exactly — they are intolerant of sudden changes. A pack of 8 in a 300-litre display will noticeably reduce aiptasia within four weeks, with full eradication in 8-12 weeks assuming no predators.
Their main predators in a reef tank are wrasses (every species), peppermint shrimp (sometimes), and larger hermit crabs. A fish-free reef or a tank with only gobies and small clownfish gives berghias the best chance.
Water Quality for Slugs
Nudibranchs are intolerant of ammonia spikes, copper, and salinity swings. Do not introduce any nudibranch to a tank under six months old. Full reef-grade parameters — nitrate under 10 ppm, phosphate under 0.05, calcium 420-440, alkalinity 8-9 dKH. Temperature 25 °C steady. In our Singapore tanks, the chiller is the single most important piece of equipment for keeping berghias through a hot week.
What Happens When Food Runs Out
Berghias that clear all the aiptasia in a tank will slowly starve over the following weeks — they cannot switch prey. Hobbyists with effective colonies typically trade survivors back to other keepers with ongoing aiptasia problems. This is part of the responsibility of keeping the species: plan the exit before you buy them.
Breeding Berghia at Home
Berghias lay spiral egg ribbons on glass. A dedicated 10-litre species tank with a continuous aiptasia supply, gentle air, and matched reef water will produce juveniles within weeks. Feed the adults daily-to-three-times-weekly with aiptasia scraped off a host rock you maintain in a separate refugium. A small breeding operation produces enough juveniles to trade for credit at friendly local shops.
The Ethical Summary
Most nudibranchs seen for sale in Singapore shops are wild-caught ornamentals that will die within two months. Do not buy them. Berghia and lettuce slugs are the rare exceptions where captive husbandry is genuinely viable. If the animal in front of you does not match one of those two categories, take a photo, admire it, and leave it in the shop for someone else’s disappointment.
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emilynakatani
Still Have Questions About Your Tank?
Drop by Gensou Aquascaping — most walk-in questions get answered in under 10 minutes by someone who has set up hundreds of tanks.
5 Everton Park #01-34B, Singapore 080005 · Open daily 11am – 8pm
