Aquarium glossary

Rolly pollies

Polyp ball dropout
DefinitionRolly pollies are polyp balls that detach from a parent zoanthid colony or mushroom coral and roll across the substrate. They re-attach within days and grow into new colonies.

In depth

Rolly pollies (also called pedal lacers) are how zoanthids + mushroom corals reproduce asexually. What happens: a polyp pinches off its base, leaving a small "ball" (1-3mm) that tumbles in current. Where they go: rolls until lodging in a low-flow crevice, then attaches. How to encourage: 1) low flow areas in the display. 2) small frag plugs scattered at the base of the parent. 3) avoid current that flushes them out. How to harvest: place plastic mesh or "polyp catcher" disc near the parent - new pollies attach to it. Common producers: Rhodactis mushrooms, Discosoma, common zoanthids (eagle eye, fire and ice). Less common: Ricordea florida + ricordea yuma divide internally rather than dropping pollies. Asexual vs sexual reproduction: rolly pollies are clones - same genetics. Sexual reproduction in coral is rare in home aquariums; mostly limited to broadcast spawning events in mature systems.

Reviewed by the Fast Aquatics husbandry team · Updated May 2026

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Aquarium-keeping fundamentals

Whatever specific topic brought you here, four fundamentals govern long-term aquarium success: water quality, parameter stability, biological filtration, and species-appropriate husbandry. Skip any one and the others struggle to compensate.

Water quality: ammonia + nitrite at zero, nitrate under 30 ppm freshwater + 10 ppm reef. Test weekly with API or Salifert kits. Use our water parameter checker to score your readings against your tank type.

Parameter stability: stable wrong parameters beat fluctuating ideal parameters. Most fish tolerate a wide pH range if it's stable. Sudden swings of 0.4+ pH or 5+°F kill fish faster than chronic suboptimal values. Use temperature controllers (Inkbird) + automated dosing for consistency.

Biological filtration: the bacterial colony on your filter media + rock + substrate is the engine. Never replace all media at once. Use our filter turnover calculator to size correctly.

Species-appropriate husbandry: research adult size, territoriality, diet, and tankmate compatibility before purchase. Use our tank stocking calculator + compatibility guides.

Frequently asked questions

How long does an aquarium take to set up? 4-6 weeks for full cycling + first stocking. Use our cycle ETA calculator + how long does cycling take.

What's the best aquarium for beginners? 20-gallon long. Big enough for parameter stability, small enough for budget + space. See beginner picks.

How often should I do water changes? 25-30% weekly. See water change frequency Q&A + water change calculator.

Why does my fish keep dying? 5 leading causes: uncycled tank, wrong species pairings, no quarantine, undersized tank, neglected water-change schedule. See full diagnosis.

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