Copper Safe 45 Day Fallow Reef Protocol
Fallow is not punishment — it is the cleanest way to break a parasite cycle on a tank you cannot medicate. A copper safe 45 day fallow reef period keeps your corals and invertebrates unharmed while letting unattached parasites starve in the display, and it pairs perfectly with separate quarantine and treatment for the fish themselves. This protocol from Gensou Aquascaping at 5 Everton Park lays out the timing, holding logistics, and re-entry sequence we use on client reefs that have had an ich outbreak or are preparing for a reset before adding new stock.
Why Fallow, and Why 45 Days
Marine ich and velvet need a host fish to reproduce. Without fish, the tomont stage hatches, fails to find a host, and dies within a parasite-specific window. Cryptocaryon tomonts typically complete their viable cycle within 30 to 45 days at tropical temperatures; velvet breaks cycle faster, within about 14 days. The 45-day benchmark is the conservative figure that covers both plus a safety margin. See our 72-day extended fallow guide for the maximum-conservative version if you need stronger guarantees.
Why “Copper Safe” Matters
Fallow is the only realistic disease-break for a reef display because you cannot dose copper in a tank with corals, clams, shrimp, anemones, and live rock. Copper kills invertebrates and permanently contaminates aquascape. Fallow achieves the same parasite outcome without touching the livestock or equipment you want to keep. The display stays fully operational with corals, clean-up crew and invertebrates during fallow — it is fish-free, not life-free.
Removing the Fish
Fish need somewhere to live for six weeks, and this is usually the hard part. A dedicated hospital rack with two or three 40 to 60 L tanks handles most reef stocking. Net or trap fish from the display carefully — humane fish traps like those at Reef Depot save hours compared to chasing with nets. Batch similar fish into holding tanks to avoid aggression; a chromis school in one, a pair of clownfish in another, the tang and wrasse separated if they are inclined to fight. Our humane marine fish trap guide covers the capture strategies.
Treating Fish During Fallow
Fallow works best when combined with active treatment of the fish in their holding tanks, otherwise you simply reintroduce the same parasite after fallow ends. Run copper or TTM on each holding tank for the appropriate protocol duration, completing treatment well before the 45-day fallow window closes. This gives you a clean display and clean fish ready to reunite. The TTM vs copper comparison helps choose the treatment side.
Display Maintenance During Fallow
The display continues to run normally. Water changes every week or fortnight, feeding a small amount of coral food or reduced fish-pellet to sustain the bioload, lighting on normal schedule. Corals may brown slightly from reduced nutrient input as fish waste drops; this is cosmetic and reverses when fish return. Clean-up crew stays in place and keeps working. Skimmer runs as normal but produces less output — this is also expected, not a fault. Temperature and salinity parameters remain reef-standard: 25 to 26 degrees, 1.025 SG.
The 45-Day Count
Start the clock the day the last fish leaves the display. Every fish, including small gobies hiding in rockwork, must be out; a single remaining host resets the parasite cycle. Double-check by lights-off observation and, if needed, temporarily overturning rocks during a partial drain to flush any hidden fish. Count the days conservatively — if in doubt about day zero, add three days rather than subtracting. A miscount here undoes the entire protocol.
Cryptocaryon at 25 degrees has a typical life cycle of 5 to 7 days from attachment to tomont release to new tomite hatching. Without a host, the hatching tomites die within hours. Variability comes from rogue tomonts that sit longer than average, which is why 45 rather than 30 days. A handful of studies suggest rare strains extend further still, which is why some keepers prefer 72 days for absolute confidence. For most reefs, 45 is the pragmatic balance between biological coverage and husbandry feasibility.
Avoiding Contamination Back Into the Display
Never share nets, buckets, magnet cleaners, or testing tools between the hospital rack and the display during fallow. Dedicated equipment for each system prevents re-introducing parasites at day 44. Drop tests in the display use display-only probes; siphons are labelled and not swapped. This feels paranoid, but the cost of contamination is restarting the 45-day count.
Re-Entry Day Protocol
On day 45 (or later), acclimate fish from the hospital tanks back to the display. Match temperature, salinity and pH between the holding and display water over an hour or two using drip acclimation. Introduce fish during lights-off to minimise stress and aggression, spacing additions by five or ten minutes if you have several. Our marine drip acclimation guide covers the specifics.
Monitoring After Re-Entry
Watch the display intensively for the first two weeks post-fallow. Any parasitic signs — flashing, rapid gilling, ich spots — indicate either fallow was cut short, a fish was missed in removal, or a contamination occurred. At that point you are back to the start of the cycle. Clean completions, which is most of them, show normal fish behaviour within days and remain disease-free indefinitely.
Fallow as Prevention
Some advanced Singapore reefers run a preventative fallow before major stocking events — clearing the display of all fish for 45 days before introducing a significant number of new, separately quarantined fish. This effectively gives you a reset point with known-clean fish going into a known-clean display. It is expensive in effort but eliminates most long-term parasite drama, and it is how several of the cleanest-running local reefs maintain their stock.
Kit and Logistics in Singapore
Plan for two to three 40 L holding tanks, pre-cycled sponge filters, dedicated heaters, a separate saltwater mixing station, and a commitment to hospital-rack maintenance for six weeks. Budget for around $400 to $700 in startup hardware if you do not already have a quarantine rack. Reef Depot and the Thomson marine shops stock most components; saltwater mix and RO water for top-offs through the fallow period add a small but real ongoing cost. For the capital outlay, fallow buys you a long-term parasite-free reef that is worth the six-week commitment.
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