Emergency Aquarium Care: When Things Go Wrong

Emergencies happen. Equipment fails, power goes out, disasters strike. Having a plan and acting quickly can save your fish and your tank.

Power Outages

Immediate Actions (First 30 Minutes)

Don’t panic - Most tanks can go 2-4 hours without filtration
Check the filter - Some hang-on-back filters will drain and need priming
Maintain oxygen - Surface agitation stops; oxygen depletes
Preserve bacteria - Beneficial bacteria need oxygen and flow

Short-Term Outages (2-6 Hours)

Maintain Oxygen:

Pour water into tank from height (creates bubbles)
Use battery-operated air pump
Stir surface water periodically
Remove lid slightly for gas exchange

Filter Considerations:

Canister filters: May need repriming when power returns
Sponge filters: Just reconnect air when power returns
HOB filters: May drain, have cups ready to refill

Temperature:

Wrap tank in blankets if cold weather
Float ice packs if hot weather
Monitor temperature closely

Long-Term Outages (6+ Hours)

Critical Steps:

Battery backup air pump - Essential investment
Insulation - Keep temperature stable
Bacteria preservation - Pour tank water into filter every 2 hours
Consider relocation - If outage >24 hours, temporary tank elsewhere

Generator Options:

Small inverter generator for filter/heater
Battery backup systems (UPS for aquariums)
Solar backup for critical components

Equipment Failures

Heater Failure (Stuck On - Overheating)

Signs:

Temperature rising
Fish gasping at surface
Lethargy
Rapid breathing

Immediate Actions:

Unplug heater immediately
Add ice packs in bags (gradual cooling)
Increase aeration (warm water holds less oxygen)
Remove lid to dissipate heat
Check fish for burns

Prevention:

Use heater with automatic shutoff
Check temperature daily
Have backup heater
Use temperature controller (InkBird)

Heater Failure (Broken - Cold)

Signs:

Temperature dropping
Fish lethargic
Loss of color
Gathering near heater

Immediate Actions:

Replace with backup heater
Wrap tank in blankets/towels
Place tank in warmest room
Add warm (not hot) water gradually
Use hot water bottles against tank

Tropical Fish Emergency Levels:

70-75°F: Stress zone, act within hours
65-70°F: Critical, act immediately
Below 65°F: Life threatening for most tropical fish

Filter Failure

Backup Filtration:

Sponge filter with air pump (immediate)
Internal filter (if available)
Move media to new filter
Add bottled bacteria

Preserving Bacteria:

Keep media wet (in tank water)
Provide oxygen (pour water through media hourly)
Don’t let dry out (bacteria die in 30-60 minutes without water)
Use battery air pump on media container

When Filter Won’t Restart:

Check impeller (usually stuck)
Clean impeller and housing
Check for air locks (canisters)
Test outlet with other device

Air Pump Failure

Immediate Solutions:

Pour water from height every 30 minutes
Stir surface with net
Remove some water to increase surface area
Lower water level for more surface agitation

Battery Backup:

USB air pumps ($10-15)
Battery operated pumps
Power inverter for car battery

Water Quality Emergencies

Ammonia Spike

Causes:

Cycle crash
Overfeeding
Dead fish hidden
Filter failure
New tank syndrome

Immediate Response:

Water change 50% immediately
Add ammonia detoxifier - Seachem Prime (best), AmGuard
Test tap water - Some municipal water contains chloramine that reads as ammonia
Stop feeding - Reduce bioload
Increase aeration - Ammonia reduces oxygen

Detoxifiers Explained:

Bind ammonia temporarily (24-48 hours)
Give time for bacteria to catch up
Safe for fish but ammonia still shows on tests
Dose daily until ammonia = 0

Follow-up:

Daily testing
Daily water changes if needed
Find and remove source
Reduce stocking temporarily

Nitrite Spike

Even more dangerous than ammonia!

Signs:

Brown gills
Fish gasping
Lethargy
Rapid breathing

Immediate Response:

Water change 75% immediately
Add aquarium salt - 1 teaspoon per 10 gallons
- Reduces nitrite toxicity
- Safe for most fish (except scaleless)
Add Prime - Detoxifies
Increase aeration - Critical
Daily water changes until 0 ppm

Scaleless Fish (Loaches, Corydoras, Plecos):

Use half dose of salt
Increase water changes instead
Very sensitive to nitrite

pH Crash

Causes:

Depleted KH (carbonate hardness)
Overstocked tank
Peat/acidic driftwood
Insufficient water changes

Signs:

pH below 6.0
Fish gasping
Lethargy
Death (rapid in extreme cases)

Emergency Response:

Test KH - Should be 4+ dKH
Water change 50% - Use higher pH water
Add baking soda - 1 teaspoon per 5 gallons (raises pH and KH)
Add crushed coral - To filter or substrate (long-term fix)
Monitor closely - Can rebound if KH still low

Gradual is Better:

Raise pH no more than 0.2 per day
Rapid pH changes kill fish
Even “wrong” stable pH is better than swinging pH

Fish Emergencies

Jumpers

Prevention:

Always use tight-fitting lid
No gaps around filter
Lower water level for jumpers (bettas, gouramis)

If Fish Jumps Out:

Quickly wet hands (dry hands damage slime coat)
Gently return to water
Add stress coat (API Stress Coat, Prime)
Dim lights - Reduce stress
Monitor for injuries/infection

Recovery Chances:

<2 minutes: Good (90%+ survival)
2-5 minutes: Fair (50-70%)
5-10 minutes: Poor (20-40%)
10 minutes: Very poor (use judgment)

Aggression

Immediate Separation:

Net aggressor to separate container
Rearrange tank decorations (breaks territories)
Add more hiding spots
Consider permanent separation

If Injury Occurs:

Move injured fish to hospital tank
Treat wounds with Melafix
Pristine water conditions
May need antibiotic if infected

Mass Death Event

If multiple fish die suddenly:

Test water immediately - Full panel
Check for contaminants:
- Air fresheners/sprays nearby?
- Hands washed with soap before tank work?
- New decorations not rinsed?
- Children put something in tank?
50% water change with Prime
Remove dead fish immediately
Don’t add new fish until cause found

Natural Disasters

Hurricanes/Storms

Preparation:

Battery backup air pumps (multiple)
Generator if possible
Insulation blankets
50-gallon bins for temporary housing
Water storage (aged, treated)

During:

Monitor temperature
Battery pumps running
Check for leaks from pressure changes

Earthquakes

Immediate:

Check for leaks/cracks
Secure stand (if still standing)
May need to drain partially if unstable
Evacuate fish to buckets if tank compromised

Evacuation

If you must leave:

Fish in buckets with lids (1-2 gallons each)
Battery air pumps
Water conditioner
Some food
Test kit

Temporary Setup:

Large plastic bins work as emergency tanks
Keep filter media wet
Battery air essential
Return ASAP

Emergency Kit Checklist

Keep Stocked Always:

Water Treatment:

Seachem Prime (ammonia detoxifier)
Aquarium salt
Baking soda (pH emergency)
Epsom salt

Testing:

API Master Test Kit
pH test (separate)

Equipment:

Medications:

Broad spectrum antibiotic (Kanaplex)
Parasite treatment (ParaGuard)
Fungus treatment
Stress Coat

Tools:

Prevention is Everything

Best Emergency Response: Never having one

Prevention Checklist:

When to Euthanize

Humane euthanasia is appropriate when:

Dropsy with pineconing (kidney failure)
Severe, untreatable injuries
Chronic suffering with no improvement
Multiple organ failure

Humane Method (2026):

Clove oil (eugenol) bath
Mix 10 drops per gallon
Fish peacefully goes to sleep
Freezing is NOT humane

Conclusion

Emergencies are stressful, but preparation and quick action save tanks. Keep emergency supplies, know your procedures, and stay calm.

Golden Rules:

Water changes solve 80% of problems
Prime is your emergency friend
Never panic - most fish are tougher than you think
Preparation prevents emergencies
When in doubt, water change

Remember: Every experienced aquarist has faced emergencies. Learn from each one, prepare better, and you’ll handle the next one with confidence.

Last Updated: January 2026
Next Review: July 2026