Caring for Starfish in a Home Aquarium: Dos and Don’tsStarfish (commonly called sea stars) are charismatic, slow-moving invertebrates that can add color and interest to a marine aquarium. However, keeping them healthy requires specific water conditions, proper diet, compatible tankmates, and careful husbandry. This guide covers practical dos and don’ts, common problems, setup suggestions, and brief species notes to help you succeed.
Do: Research species before buying
Not all starfish thrive in captivity. Some species are hardy in aquaria (e.g., Fromia, Linckia), while others (e.g., many cushion and brisingid stars) are nearly impossible to keep. Check growth potential, diet, and known captive-care history.
Don’t: Buy without knowing its feeding needs
Starfish vary widely in diet. Some are detritivores or scavengers; others are predators that eat corals, clams, or snails. Buying a coral-eating species for a reef tank will cause problems. If unsure, avoid species with unknown diets.
Do: Provide stable water quality
Starfish are sensitive to changes in salinity, temperature, ammonia, nitrite, and nitrate. Aim for:
- Salinity: 1.023–1.025 SG (specific gravity)
- Temperature: 75–78°F (24–26°C) for most tropical species
- Ammonia/nitrite: 0 ppm
- Nitrate: keep below 10–20 ppm where possible Use a reliable test kit, perform regular partial water changes (10–20% weekly or biweekly depending on bioload), and provide gentle water flow.
Don’t: Allow rapid water parameter swings
Even small, fast changes in salinity or temperature can be fatal. When doing water changes, match temperature and salinity closely; add water slowly to avoid shock.
Do: Ensure adequate tank size and acclimation
A stable, mature aquarium reduces risk. Starfish do best in tanks that have been cycled for several months with established microfauna. Minimum recommended tank size is often 30 gallons for small species; larger species need much more space. Acclimate slowly using drip acclimation for at least 1–2 hours.
Don’t: Add starfish to brand-new setups
New tanks are more likely to have unstable chemistry and insufficient food sources. Introducing a starfish too early risks starvation or poisoning from ammonia/nitrite spikes.
Do: Offer appropriate substrate and hiding places
Many starfish appreciate rockwork and sand where they can move and forage. Provide live rock to support microfauna and grazing opportunities. Avoid very fine stirring sand that may clog tube feet; choose a grain size suited to the species.
Don’t: Keep them with aggressive or predatory tankmates
Avoid housing starfish with large crabs, some wrasses, puffers, or aggressive fishes that may pick at or injure them. Some crabs can prey on weakened stars.
Do: Feed according to species
Feed target-specific diets:
- Detritivores/grazers (e.g., Fromia): small bits of meaty foods, algae wafers, and naturally available microfauna on live rock.
- Carnivores/predators: whole mollusks, shrimp, or prepared meaty diets; some will prey on corals. Feed small amounts frequently rather than large portions. Monitor to ensure the starfish is actually eating—some species feed at night or are slow to accept prepared foods.
Don’t: Overfeed or underfeed
Overfeeding increases waste and nitrate levels; underfeeding leads to starvation (common even in tanks with visible algae because captive diets differ). If your starfish is not visibly feeding, research alternatives or consider removal to a species-appropriate system.
Do: Handle minimally and carefully
Starfish are delicate. If you must move one, support it fully and keep handling time brief. Wet hands only; never expose them to air for longer than necessary.
Don’t: Pick them up for photos or display often
Air exposure and rough handling damage their tube feet and skin. Frequent handling stresses them and increases infection risk.
Do: Quarantine new additions
Quarantine starfish and other invertebrates in a separate tank for observation (2–4 weeks) to watch for disease, parasites, or pests and to acclimate them slowly.
Don’t: Assume visible health equals long-term suitability
Some species appear healthy but have hidden dietary needs that will cause decline weeks later. Monitor behavior: active foraging, normal arm extension, and firm attachment to surfaces are good signs.
Do: Watch for signs of illness and act fast
Signs of trouble include limb curling, reduced movement, disintegration, loss of attachment, white lesions, or tissue sloughing. If observed:
- Check water parameters immediately.
- Improve water quality with water changes and testing.
- Isolate the animal if contagious disease is suspected.
- Seek species-specific treatment advice (e.g., freshwater dips for some bacterial infestations, but only under guidance).
Don’t: Use medications without research
Many aquarium medications and copper treatments are lethal to echinoderms. Only use treatments known to be safe for starfish, and preferably under advice from experienced hobbyists or a vet.
Do: Maintain tank biodiversity for natural food sources
Live rock, sand microfauna, and a healthy biofilm support many starfish diets. Encouraging a balanced micro-ecosystem helps detritivores and grazers thrive.
Don’t: Rely solely on artificial foods for all species
Some species require live prey or the microorganisms found on live rock and sand. If you can’t provide that, choose species known to accept prepared diets.
Quick species notes
- Linckia laevigata (Blue star): moderately hardy, grazes on biofilm and detritus; popular but still needs stable water.
- Fromia spp.: often hardy but may need frequent feeding with small meaty items.
- Asterina spp.: small, prolific; some are pest-like but others are harmless scavengers.
- Cushion stars, brisingids, and many deep-water species: generally poor candidates for home aquaria.
Starfish can be rewarding additions to marine aquaria if chosen and cared for correctly. Prioritize species research, stable water quality, appropriate diet, minimal handling, and compatible tankmates. With the right setup and attention, many starfish will live for years and become fascinating members of your reef or marine tank.
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