Quarantine setup for $15

A plastic tub, a sponge filter, and a heater you already own. Quarantine doesn't require a second tank, and skipping it costs more than setting it up.

Every fish disease guide says "quarantine new fish." Most fishkeepers skip this because they think quarantine requires a second aquarium, a second filter, a second heater, and a dedicated stand. It doesn't. The entire setup costs less than treating one outbreak of ich in your display tank.

What you need

A clear plastic storage tub: $5-8. A 40-liter (10-gallon) Sterilite or similar food-safe tub from any big-box store. Clear plastic lets you observe the fish. Mark gallon or liter lines on the outside with a permanent marker so you can dose medications accurately. No substrate, no decorations, bare bottom. You want to see the fish clearly and clean the tub easily.

A sponge filter: $5-8. A small air-driven sponge filter. Seed it by running it inside your main tank for 2-4 weeks before you need it. When quarantine time comes, move the sponge to the tub. It carries over enough beneficial bacteria to handle the bioload of a few small fish immediately. After quarantine, move it back to the main tank to stay seeded.

An air pump: $8-15 (if you don't already have one). Many fishkeepers already have an air pump. If not, a small USB-powered pump costs $8. This drives the sponge filter.

A heater: $0 (borrow from the main tank, or use a spare). If your quarantine period is short (2-4 weeks) and the room stays above 20°C, most tropical fish tolerate room temperature. If the room is cooler, move the heater from the display tank temporarily, or buy a basic 50W adjustable heater for $10-15.

Hiding spots: $0. A terracotta pot on its side, a PVC pipe section from the hardware store, or a plastic plant from the display tank. Fish stress in open, empty spaces. One or two cheap hides reduce stress and let you observe behavior (is the fish hiding all the time, or coming out to explore?).

Total if you own nothing: roughly $20-25. If you already have an air pump and a spare heater: $10-15.

How to use it

When new fish arrive:

1. Fill the tub with dechlorinated water at the same temperature and approximate parameters as your main tank.
2. Move the seeded sponge filter from the main tank to the tub.
3. Acclimate the new fish to the tub water (float the bag for temperature, then drip-acclimate or add small amounts of tub water to the bag over 20-30 minutes).
4. Observe for 2-4 weeks. Feed lightly. Do 25-30% water changes every 2-3 days.

What you're watching for: white spots (ich), fuzzy patches (fungus), fin rot, clamped fins, rapid breathing, flashing (scratching against surfaces), or refusal to eat. Any of these in quarantine means you treat the tub, not your display tank. The medication dosing calculator gives accurate dosing for the tub volume.

If everything looks healthy after 2-4 weeks, move the fish to the display tank. Drain the tub, wipe it down with vinegar, rinse, dry, and stack the sponge filter back inside. The whole setup stores in a closet.

Why skipping costs more

Ich treatment for a 200-liter display tank costs $15-25 in medication, plus days of elevated temperature (more electricity), plus the stress on existing fish, plus potential losses. A single disease introduced by an unquarantined fish can cost more in medication and dead livestock than 10 quarantine setups.

Columnaris, camallanus worms, and drug-resistant strains of ich are difficult or impossible to treat in a display tank full of plants, shrimp, and established fish. Some medications kill invertebrates. Some kill plants. Some require removing carbon from the filter. In a bare quarantine tub, none of those constraints exist. You treat aggressively, the disease stays contained, and your display tank never knows it happened.

The quarantine tub is the cheapest insurance in the hobby.

What quarantine catches

The most common diseases prevented by quarantine:

Ich (white spot disease). Visible as small white dots on fins and body. Symptoms appear 3-7 days after exposure. A 2-week quarantine period is long enough for ich to show itself if the fish is infected.

Velvet (Oodinium). A gold or rust-colored dusting on the fish's body, often visible on the fins first. Can be subtle in early stages. Affected fish may clamp their fins and scratch against surfaces.

Internal parasites. Thin, active fish that eat eagerly but don't gain weight may have internal parasites. These aren't visible externally but the fish's condition becomes apparent during a 2-4 week observation period. Medicated food (containing praziquantel or levamisole) during quarantine treats internal parasites prophylactically.

Bacterial infections (fin rot, columnaris). Stress from shipping and store conditions often triggers bacterial infections that were subclinical. Quarantine gives these time to surface while the fish is in a controlled environment where you can treat without medicating your display tank.

A standard quarantine protocol

Week 1: Observe. Feed lightly. Monitor for visible symptoms. Test water daily (ammonia can spike in an uncycled quarantine tank; do 25% water changes if ammonia exceeds 0.5 parts per million).

Week 2: If the fish appears healthy, continue observing. Some experienced fishkeepers dose prophylactic medication during this week: a combination of praziquantel (for internal parasites) and erythromycin or kanaplex (for bacterial infections). This "treat everything" approach is debated, but it's common practice in the competition cichlid and discus communities.

Week 3-4 (optional but recommended): Continue observation. If no symptoms appear after 3-4 weeks, the fish is almost certainly safe to transfer to the display tank. The longer quarantine catches slow-developing infections that a 2-week window might miss.

The cost of skipping quarantine

A $5 fish that introduces ich to your 200-liter display tank can result in the loss of $50-200 worth of existing fish, plus the cost of medication, plus the stress of managing a disease outbreak in a fully stocked tank. A $30 quarantine setup pays for itself the first time it catches a sick fish before it reaches the display tank.

The medication dosing calculator helps you dose treatments accurately for your quarantine tank volume.

The quarantine tank doesn't need to be pretty. It needs to be functional, ready to deploy, and used consistently for every new addition.