Aquarium livestock evacuation: tank failure procedure including bacteria preservation

The four categories of evacuation

• Same-day return (under 24 hours). Minor repair or partial reseam where the tank is back in service within a day. Holding can be informal - storage totes, single sponge filter, heater. Bacteria are fine.
• Short-term hold (1-7 days). Glass overlay repair, single seam reseam, minor crack stabilization. Holding requires proper aeration, heating, and feeding routine. Bacteria need active media transfer.
• Long-term hold (7-30 days). Full tank reseam, glass panel replacement, tank replacement order. Holding becomes a temporary system requiring its own water changes and parameter management.
• Permanent transfer. Tank cannot be repaired and replacement is delayed indefinitely, or livestock is rehomed. Different procedure - you are basically setting up a new long-term home.

Decide which category you are in before you start. The setup for each is different.

Holding container shopping list

Most evacuations use plastic storage totes plus a few key pieces of life support. The Sterilite 18-gallon clear tote ($9 at Home Depot) is the standard. Sizing:

You do not have to match original volume one-to-one. Reduce by 30-50% as long as livestock has room to swim and the bioload is manageable.

Container recommendations:

• Sterilite 18-gal clear totes - $9 each, food-grade HDPE, see-through for monitoring
• Rubbermaid Brute 32-gallon trash cans - $35 each, food-grade HDPE, taller form factor good for large cichlids
• Rubbermaid 100-gallon Structural Foam stock tank - $180 at Tractor Supply, designed for livestock water, ideal for monster tank evacuation
• Cooler (Coleman, Igloo, Yeti) - 50-150 gallons, food-grade insulated, but insulation works against you for short holds because temperature does not equilibrate easily

Avoid: garbage cans not labeled "food grade", any container that has held chemicals, any container with a printed label or pigmented plastic dye (industrial totes leach plasticizers).

Life support for the holding tank

Holding livestock alive for 7-14 days requires proper aeration, heating, and biofilter. Minimum kit:

• Heater sized to the holding container. Eheim Jager 100W or 150W for 10-25 gallon totes ($30 each), 200W or 300W for 30-50 gallon totes ($40-55).
• Air pump and airstone. Tetra Whisper AP150 ($35) drives 3-4 airstones, enough for one large tote or two small ones.
• Sponge filter (the critical bacteria component). ATI Hydro-Sponge filters in size IV or V ($12-15 each) run off the air pump. Squeeze them in your original tank water before transfer to preserve bacterial colony. One sponge per 20 gallons of holding water minimum.
• Submersible pump or powerhead. Optional but useful for water movement in larger holding setups. Hydor Koralia ($25) or AquaClear powerhead.
• Light coverage. Any LED strip light, but optional - livestock tolerates 7-14 days of low light fine.
• Lid (cracked open for gas exchange). Important to prevent jumpers (loaches, hatchet fish, eels). A piece of egg crate (light diffuser) cut to fit is the standard.

Total life-support cost for a 75-gallon evacuation: $80-150 if you do not already own the kit. Many of these are tools you should own anyway.

Bacteria preservation: the critical step nobody talks about

Your established biofilter is the most valuable thing in your aquarium. A 6-month-old colony of nitrifying bacteria represents thousands of dollars in livestock potential. Lose it and you re-cycle the tank, exposing all your fish to ammonia spikes.

Bacteria live primarily on filter media surfaces - sponge, ceramic, bioballs, K1 - not in the water column. To save them, you move the media into the holding container with proper conditions.

1. Squeeze your existing filter media in the original tank water to release the bacteria-bound biofilm into the water. This water is gold; use it to fill the holding container.
2. Transfer the squeezed filter media to the holding container. Place media in a mesh bag (no-see-um material, $5 / yard, sold for kratky pots) and submerge it where flow from the air-driven sponge filter passes over it.
3. Keep the media wet, oxygenated, and at temperature. Bacteria die rapidly when dry, anaerobic, or cold.
4. Do not feed for the first 24-48 hours of holding if possible. This reduces the ammonia load on the displaced biofilter while it re-establishes flow conditions.
5. Test ammonia every 12 hours for the first 4 days. Seachem Prime dose if any detectable ammonia. Each Prime dose binds up to 1 ppm ammonia for 24 hours, buying the bacteria time to catch up.

For substrate-heavy tanks (planted aquariums, deep-sand-bed reef), the substrate also carries bacteria. Bag substrate in 5-gallon buckets with tank water and a sponge filter for the duration. Bagged substrate keeps bacteria alive for about 72 hours.

Capture order: who comes out first

Order matters in an active emergency. The wrong order can mean the difference between a healthy evacuation and dead fish.

1. Pull all loose decor first. Rocks, driftwood, plants come out before fish. Reduces hiding spots so fish are catchable.
2. Catch the most stressed-looking fish first. Fish at the surface gasping, fish hiding in unusual spots, fish with visible injury from the failure event.
3. Catch jumpers next. Hatchet fish, loaches, eels, killifish - they leap out of dropping water and die on the floor. Cover the tank surface with a wet towel between captures to prevent jumps.
4. Catch territorial bullies next. Removing dominant cichlids reduces stress on the rest of the tank during the chaotic capture phase.
5. Catch schoolers in groups. Tetras, danios, rasboras - net 5-6 at once. Schooling fish handle group transfer much better than solo transfer.
6. Bottom dwellers last. Plecos, corys, loaches stay calm at the bottom; capture them after the water level is low.
7. Invertebrates and corals separately. Shrimp and snails into their own container. Corals attached to rock can travel with the rock; corals attached to the tank glass need careful chisel-pry.

For very valuable or sensitive specimens, hand-cup them rather than netting. A glass or plastic cup pushed slowly underwater with the fish inside avoids the fin damage and slime-coat stress that nets cause.

Transfer technique - matching parameters

The holding water should match the tank water at the moment of transfer. Specifically:

• Temperature within 2 F. A heater in the holding tote brought to original tank temperature 4-6 hours before transfer.
• pH within 0.3 units. Use the original tank water as the fill water for the holding tote. Do not use fresh tap water as the base for a holding emergency - it lacks the buffering chemistry and the bacterial conditioning of established water.
• Salinity within 0.5 ppt for marine. Marine evacuations should use original tank water exclusively; fresh saltwater mix is too different chemically.
• Hardness within reasonable range. Less critical for short-term but matters at the 7-14 day mark.

Drip acclimation back into the tank when livestock returns. Drip line, 2-3 drops per second, across 30-60 minutes. Yes, even though it is the same fish going back into the same physical space - the holding water has drifted, and the tank water during the repair has drifted, and you should treat the reintroduction as a new fish.

Holding tank parameter management

Across 7-14 days the holding tote will accumulate waste and drift from initial parameters. Manage actively:

• Test ammonia and nitrite daily. API Master Test Kit reads both. Any reading above 0.25 ppm calls for an immediate water change or Prime dose.
• Water change weekly minimum. 25-30% with conditioned, temperature-matched water. Use tap dosed with Seachem Prime, or RO/DI for sensitive species.
• Feed lightly. Half normal ration. Less food = less ammonia. Fish lose minor weight over 14 days but recover quickly when restocked.
• Monitor for jumpers, escapes, and aggression. Cramped holding can trigger fighting among territorial fish. Separate troublemakers into individual buckets if needed.
• Watch for disease. Stress from evacuation suppresses fish immune systems. Ich, fin rot, and bacterial infection peak at days 4-8 of holding. Watch for white spots, frayed fins, cottony patches.
• Top off evaporation daily with dechlorinated water.

Coral and invertebrate-specific procedures

• Hard corals (SPS, LPS). Transport on their rock when possible. Keep moist; submerge during transit. Frags on plugs travel best in a frag rack inside a small acclimation container.
• Soft corals (mushrooms, zoanthids, leathers). More tolerant of brief exposure. Wear nitrile gloves - palytoxin from some zoanthid genera is a known hazard.
• Anemones. Tricky. Most anemones hold tight to substrate; gently detach with a credit card edge. Bag with tank water and air for short transfer. Long holding requires their own lit container with original parameters.
• Cleaner shrimp, peppermint shrimp, fire shrimp. Net carefully or hand-cup. They tolerate evacuation reasonably well.
• Crabs. Pin and net; they shed limbs under stress. Hermit crabs travel in their shells fine.
• Marine snails. Pull off the glass with a credit card if attached. Handle gently; cracked shells expose tissue.
• Freshwater shrimp (cherry, crystal, sulawesi). Float a small container in their own water - they can be hard to net. Move with substrate plant matter as cover.

Return to repaired tank: the 2-3 day staged plan

Do not move all livestock back at once. Stage the return.

1. Day 0: tank refilled, equipment running. Test ammonia, nitrite, nitrate. Verify temperature stable. Verify no residual silicone vinegar smell.
2. Day 1: hardiest fish back. Plecos, corydoras, hardy tetras, livebearers. Drip acclimate 30 min. Watch for 24 hours.
3. Day 2: mid-tier fish back. Schoolers, gouramis, smaller cichlids. Drip acclimate 30 min. Watch.
4. Day 3: sensitive species back. Discus, wild-caught, dwarf cichlids, marine fish, corals. Drip acclimate 45-60 min.
5. Days 4-7: monitor for ammonia spike. Bacterial colony may need to catch up to the full bioload. Daily testing. Dose Prime as needed.
6. Day 7-14: resume normal feeding and water changes. Watch for delayed stress-related disease (ich emergence is common at this window).

When to send livestock to your LFS

For evacuations that will run longer than 14 days, or for high-value reef livestock, consider boarding at your local fish store. Many LFSs offer holding service at $1-3 per gallon per week, or $5-15 per fish for the duration.

Pros: stable parameters, no risk to your floor or your sleep, professional disease monitoring, equipment-failure resilience.

Cons: cost, risk of disease cross-contamination from store stock, transport stress on the way there and back.

For coral specifically, many reef-specialty stores will hold high-value frags for free in exchange for fragging rights when you return. This works out well for SPS hobbyists.

FAQ

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• Silicone reseal walkthrough