A practical hospital tank needs enough volume for the fish, stable temperature, strong oxygenation, simple shelter and a way to control ammonia. A seeded sponge filter is ideal when available, but some medications can affect beneficial bacteria, so testing remains essential. Keep décor minimal, calculate doses from actual water volume and dedicate nets or siphons to the hospital tank to reduce cross-contamination.
The point of a hospital tank is control. You want to see the fish, measure the water, dose accurately and clean the system without disturbing a complex aquascape.
Basic equipment
- Appropriately sized tank or food-safe treatment container.
- Heater and thermometer for species that require stable warmth.
- Sponge filter or other gentle filtration plus aeration.
- Lid or cover for jumping species.
- PVC elbows, ceramic pots or other inert easy-clean shelter.
- Dedicated net, siphon and test kit.
Seeded filtration helps but is not a guarantee
A mature sponge or other biological media can reduce ammonia risk, but only use media from a healthy disease-free system. Some medications or disinfectants can damage the biofilter.
Test ammonia and nitrite daily when the tank is newly set up or medicated.
Keep the bottom bare
A bare bottom makes faeces, uneaten food and parasites easier to see and remove. It also prevents substrate from absorbing medication or hiding waste.
For species that become stressed on a reflective bottom, place a dark mat outside the tank rather than adding difficult-to-clean substrate.
Match the main tank before moving the fish
Temperature and basic water chemistry should be close enough to avoid a second stress event. Acclimate when there is a meaningful difference rather than making abrupt changes.
Once treatment begins, follow the medication instructions for water changes and redosing.
Prevent cross-contamination
- Do not move the hospital net back to the display tank without disinfection.
- Wash hands between systems.
- Keep treatment water away from other aquariums.
- Clean or disinfect equipment appropriately after the case is finished.
Frequently asked questions
Does a hospital tank need to be cycled?
A mature biofilter is helpful, but treatment tanks are often temporary. If uncycled, frequent testing and water changes are essential.
Can I use a plastic tub?
A suitable food-safe container can work if it holds temperature, oxygenation and water safely and the fish has enough room.
Should I add gravel?
Usually no. Bare-bottom setups are easier to observe, clean and dose accurately.
Sources and further reading
This guide separates general aquarium arithmetic from fish-welfare decisions. For species-specific limits, always check the needs of the fish you intend to keep.