This is the process of adding and establishing fishes to an aquarium. There are many opinions on this and there is science, the science is best discussed on other aspects of the website to prevent confusion. So this page comes with a certain disclaimer of my experience.

May I just say with my experience I personally feel the plop and drop is better, any acclimatisation is rapid whether it be 1 minute or 12 hours, all are stressful but the shorter the time period the quicker the fish can adapt without more change being submitted onto it.

But what is the plop and drop you might ask.

This is either pouring the water from the bag into a net so catching the fish in that net which they are then added to the tank or handling the fishes from the bag in. I have done this successfully with fishes whether it be a shipping time of 48 hours or a 30 minute drive. The issue is with long and even an hour (ish) journeys should they be in their waste any longer even if it’s being diluted and on exposure to air the pH rapidly changes and produces the more toxic ammonia opposed to the ammonium. The process of dripping is stressful as it’s prolonged acclimatisation exposed to air, the prolonged acclimatisation I have experienced as triggers for self poisoning events in catfishes. At the end of the day it’s quick and the fish can be left alone soon after arriving.

Floating the bag is common and not a bad idea if the bag isn’t opened for the reasons I mentioned above, generally as long as the temperatures aren’t diversely different the fish will be fine. On fishes in cold water they do need to be out of that stone cold quickly as I’ve found that as lethal as sudden pH changes.

For biosecurity reasons I don’t recommend dipping a floating bag in the water the fish is already in, every dip down to mix the water is a change and risks exchanging parasites. Not that any method of acclimatisation is ever low in that.

Should I treat fishes when they arrive?

Most reliable stores should have already treated their fishes many times so this shouldn’t be a worry. Resistant diseases will exist and likely only encouraged by more frequent treating. It’s a big topic though with a lot of debate. I personally do not for a variety of reasons I can discuss elsewhere on the website.

Do I switch off the lights and for how long?

I would during and while the fish are in the aquarium, sudden lighting changes can spook fishes. There is no set time. I tend to wait an unpredicted amount of time. With easily spooked fishes I tend to do it when the tank is in the brightest spot.

When should I feed?

Keep it low and build up to desirable amounts with time. This is much more important with a new aquarium. Some fishes do need a lot more food then others such as discus or more herbivorous plecos (Loricariids) so not the greatest as a first fish.

Don’t disturb the aquarium when the fish are newly added!

Water changes are usually fine the day after with a water change but the day the fish is added it can be very much a good idea. Fast and bold movements around an aquarium can spook fishes for a long time, some more then others leading to damage but at first many fish wont appreciate it. It’s best to build any of these movements over time, I have my aquariums where I work when at home with a moveable desk so they know I am always there and mean no harm. It also means I do not always mean food so I see more natural behaviours, mainly an issue with pufferfish and cichlids.