Adding fish to the aquarium

When you get the fish home from the shop, immediately place the bag(s) in the aquarium to let temperatures start to equalise.

Then go take your jacket off, put the kettle on and make your preparations for adding the fish to the tank. I use a clothes peg and a small glass.

Open the bag and fold down to form a collar. I peg this to a bracing bar in the tank so the filter flow doesn’t move it round to some inaccessible corner of the tank.

After about ten to twenty minutes start topping up the bag with tank water. Add a small amount every 10-15 minutes until you’ve at least doubled or even tripled the amount of water in the transport bag.

Don’t rush this stage. For particularly sensitve fish you should try to make sure your tank water matches that of the supplier but even then, spending an hour or two at this can save expensive and disappointing losses. Marine fish and inverts in particular benefit from this.

Add the fish by tipping the bag over and allowing the fish to swim out. Trying to pour them out can lead to fish trapped in the corners of the bag. The fish swim against the current, into the bag, and as the water goes out the bag collapses, trapping the fish. They can be encouraged to leave by very slowly lifting the bottom of the bag.

The fish will generally try to hide before coming out and exploring their new environment but sit back and be patient.