Look for ¼ inch (6mm) vinyl hose at a pet store, or the faucet and sprinkler section of a home improvement store. You only need enough to transfer water from the tank to the other container.
 Tie a simple overhand knot in the tubing. Place one end in the aquarium and the other in an empty bucket, lower down. Suck on the dry end to get the siphon started, then watch the flow. Tighten or loosen the knot until only a drip comes out, aiming for about 1 drip per second.


You may use a clamp instead to clamp the tube nearly closed.
 Stand the bag in a fish-safe container that holds ½ to 1 gallon (2–4 liters). Gently pour the water and fish from the bag into the container. If the water would be too shallow for the fish, just stand the open bag upright with the fish inside.
 Siphon the tank water again, this time into the container with the fish. Let it fill up until you've transferred ½ gallon (2 liters) of aquarium water.
 Do not pour any water back into the tank, as it may contain undesirable substances or organisms from the pet store.
Purchase small vinyl tubing.
Knot or clamp the tube to reduce flow.
Place the fish in a separate container.
Siphon water with the tubing.
Transfer the fish with a net.
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