How to Set Up a Hospital Tank: Beginner Guide to Fish Treatment

When a fish falls ill, medicating the entire display tank risks harming healthy inhabitants, crashing the nitrogen cycle, and staining silicone. A dedicated hospital tank solves all three problems. This set up hospital tank beginner guide from Gensou Aquascaping Singapore, 5 Everton Park, shows you exactly what you need and how to use it. With over 20 years of hands-on experience, we consider a hospital tank essential kit for every serious hobbyist who wants to set up hospital tank readiness.

What a Hospital Tank Is (and Is Not)

A hospital tank is a temporary, bare-bones treatment enclosure. It is not a permanent home. Its purpose is isolation, observation, and medication — nothing more. Aesthetics do not matter here. Function matters. Think of it as the aquatic equivalent of a clinic bed: clean, minimal, and purpose-built.

Choosing the Right Size

A 20–40 litre tank suits most freshwater species commonly kept in Singapore. Smaller fish like tetras and rasboras need only 15–20 litres. Medium-bodied species — gouramis, angelfish, or larger barbs — benefit from 30–40 litres for comfortable recovery. A basic glass tank costs $10–25 locally and stores flat when not in use.

Avoid anything under 10 litres. The tiny water volume makes temperature and water chemistry dangerously unstable, especially in Singapore’s 28–32°C ambient conditions.

Essential Equipment

Keep the setup simple. You need a sponge filter (pre-seeded from your main tank’s filter media for instant biological filtration), an air pump, airline tubing, and a thermometer. A small adjustable heater is useful if you run air conditioning below 24°C overnight. Skip substrate — bare bottoms allow you to monitor waste output and spot parasites or abnormal faeces immediately.

Provide one or two hiding spots using PVC pipes, terracotta pots, or a clean mug. Stressed, sick fish recover faster when they feel secure. Do not use activated carbon in the filter during treatment — carbon adsorbs medication from the water.

Water Preparation

Fill the hospital tank with dechlorinated PUB tap water, matching temperature and pH to your main tank as closely as possible. Singapore’s tap water is soft and slightly acidic (pH 6.5–7.0), which suits most tropical species. Treat with a conditioner that neutralises chloramine — Seachem Prime is the most popular choice among local hobbyists at around $8–15 per bottle.

If you need the tank urgently and lack seeded filter media, dose a bacterial starter product and perform daily 50% water changes to manage ammonia manually until the cycle establishes.

Common Medications and Their Uses

Stock a small medicine cabinet. Methylene blue ($5–8) treats fungal infections and external parasites. Aquarium salt (non-iodised, $3–5 per box) is effective for mild bacterial infections and stress recovery at 1–3 grams per litre. Praziquantel-based dewormers tackle internal parasites. Erythromycin or kanamycin addresses bacterial infections — these typically cost $8–15 per course from local aquarium shops or Shopee sellers.

Never mix medications unless the product label explicitly permits it. Combining treatments randomly creates toxic interactions. Treat one condition at a time, with a 48-hour gap and a water change between switching drugs.

Treatment Protocol

Transfer the sick fish using a net — never pour water from the main tank into the hospital tank, as it may spread pathogens. Observe for at least 24 hours before medicating, unless the condition is immediately identifiable. Diagnose carefully: white spots suggest ich (Ichthyophthirius multifiliis), cottony growths indicate fungus, and red streaks in fins point to bacterial septicaemia.

Follow medication dosing instructions precisely. Perform a 30–50% water change before each new dose to remove metabolised medication. Maintain stable temperature throughout — fluctuations stress an already compromised immune system.

Returning Fish to the Main Tank

Only transfer a recovered fish when it has eaten normally for at least three consecutive days, shows no visible symptoms, and displays active, alert behaviour. Acclimate slowly — float a bag or drip-acclimate over 30–40 minutes to match water parameters between the two tanks.

Storage Between Uses

Rinse the tank, filter, and all accessories with hot water after each use — no soap. Allow everything to air-dry completely before storing. Keep the sponge filter running in your main tank’s sump or HOB between emergencies so it stays colonised with beneficial bacteria, ready for instant deployment. A set up hospital tank beginner guide is only useful if the equipment is maintained and available when the next illness strikes. At Gensou Aquascaping Singapore, we have seen preparation save countless fish.

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