How Long to Wait before Putting Tropical Fish In a New Tank

For a whole generation, Finding Nemo became one of the touchstone cinematic experiences. In between teaching us about parenting, growing beyond our boundaries, and that ‘P. Sherman’ does, in fact, live at “42 Wallaby Way, Sydney,” the film introduced countless children to the lives of aquarium fish.

While the film hardly pretends to be documentary-accurate in that regard (do not flush your fish thinking that you’re ‘setting them free’), it does touch on something that far too many first-time fish keepers overlook – the stress that aquarium fish can feel when being introduced into a new environment.

For that reason, and many others, you’ll need to wait a while before you can fully integrate your new tropical fish into your aquarium.

So How Long to Wait before Putting Tropical Fish In a New Tank? And what should you do to make the transition as peaceful as possible?
The transition time from purchase to full tank integration should take around 24 hours. What should you be doing during that time?

Get Your Tropical Fish Home Fast

Finding Nemo had The Tank Gang planning to roll their plastic bags out of the window and towards the ocean. In real life, not only is that essentially impossible (to put it mildly) but the longer that tropical fish remain in a bag, the worse it’ll be for them. You thus want to get them home from wherever you’ve bought them as quickly as possible.

Place the Bag in the Aquarium

Don’t just dump your new tropical fish into your aquarium. Fish tanks and the fish that live in them are notorious for being very sensitive regarding the pH and salt mixture.

Dumping your tropical fish in straight away will cause them to go from the water in their bag to the saltwater in the tank all at once – and if the difference is too great (as it likely is) at best it can stress them out or make them ill, and at worst it can kill them.

Instead, you’ll want to place the bag in the tank whole and let the aquarium water permeate the plastic bag’s membrane naturally. The water in the tank will slowly seep into the plastic bag, and that water will seep out via osmosis. This process will allow your fish to slowly get used to the pH and saltwater levels in their new home.

Battling Stress

Nemo was pretty stressed out by his new surroundings and all the strange new fish he encountered when first placed in the new tank, and that’s pretty accurate to how real-life fish can feel when suddenly plunged into a new environment. While Nemo gets over it in a cutely-animated couple of scenes, however, a sudden shock like that can prove lastingly stressful and even potentially fatal to your new fish. You will thus want to introduce them gradually to their new tank and tankmates.

If there are any territorial fish in your tank, make sure that you place your new fish in a different area of the aquarium and keep them separate during the initial 24 hours.

Keeping these factors in mind can help ensure that your new fish get along swimmingly.