With your tank fully cycled it’s finally time to start adding fish. Ideally you already have an idea of what it is you want to keep and in what quantities. However, assuming you want to have a fairly fully stocked aquarium, it’s best not to add all of the fish at once. Instead they should be added a few at a time over the course of a couple weeks. Adding all the fish at once can potentially overwhelm the filtration and lead to deaths. The only exception to this rule is if you intend to keep a large amount of particularly aggressive fish that may harass later additions if given time to claim the tank as their own. In these cases the water will just have to be monitored closely to ensure it’s parameters remain stable.
Most popular freshwater fish should be available at local pet stores. And if they aren’t in stock many stores can special order anything you want. Fish can even be ordered off the internet for home delivery. This route can be somewhat expensive, however. Likewise since you aren’t able to see exactly what it is you’re getting until it arrives the chances of getting a sick or diseased animal are somewhat higher. Whichever method you choose pick out one of the species you wish to keep for your first addition.
If you decide to buy your fish from a local store, which I recommend, there are a few things to watch for to ensure you’re getting healthy specimens. First and foremost is to assess the tanks in general. If you see lots of sickly looking or even dead fish about or if the tanks just look very unkempt you may want to find another store. Second, really check out the particular fish you are looking to buy. Make sure they are active and in good health with no problems such as torn or ragged fins, cloudy eyes, or any sores on their body. Also ask some questions of the employees such as how long the fish have been in the shop. New arrivals should be avoided as problems in new arrivals can take some time to manifest. If it’s not posted somewhere find out what type of survival guarantee they offer. Most reputable shops will offer at least a day or two. If everything passes muster pick out a few of your choosing and head for home.
Once you get your first batch of fish home the fun can begin. But before you proceed any further, turn off the aquarium lights if they are on. Also try to dim the light in the room if possible. Your fish will already be quite stressed out and bright light will only exacerbate it. Open the aquarium’s cover and float the bag in the front of the tank. For now you can leave the bag sealed. Depending on how much water is in the bag you may want to scoop some out of the aquarium first so it doesn’t overflow. Along with something for excess water you’ll want to grab a pair of scissors and some tape as well.
After the bag has been floating for ten minutes or so you can cut it open. Use the tape to secure it to the edge of the tank so it doesn’t slide in and pour out. While allowing the bag to float in the aquarium has equalized the temperature the water’s other parameters may still be different. To solve this problem, simple add some water from the aquarium into the bag. Aim for a mix of roughly 50/50 tank water and bag water. Much like the tank earlier if the bag is really full you may need to remove some water from it first. Allow the bag to sit another few minutes, then repeat the process.
With the fish fully acclimated you can now safely add them to the tank. Don’t just pour the whole bag straight into the tank though. You just want the fish, not the water. The reason is that the water that came with the fish could contain any number of things you don’t want be introducing into your aquarium such as medications or parasites. Instead, use a small net to scoop the fish from the bag and gently release them into the tank. Even once your new fish are in the tank they should still be given a few hours to relax and get comfortable with their new home. During this time leave the aquarium’s lights off.
Over the next few days your new additions should be closely monitored to look for any problems. Even if they appeared healthy when you first picked them out problems can still sometimes appear. Any fish with clear signs of disease should be removed immediately to prevent the problem from spreading. It’s also a good idea to monitor the aquarium water’s parameters just to be safe. Check the ammonia and nitrite levels just as you did during the cycling process. With a properly cycled tank these really shouldn’t be a problem but there’s no harm in making sure. If for some reason these parameters do begin to rise water changes will need to be preformed until they go back down.
After a week or two after your new fish have had time to settle into their new home you can repeat the process for your next addition. However, when adding fish to an aquarium that already has fish in it there’s one additional thing to watch for- bullying. Make sure none of the established fish are picking on the new additions. Often this habit can be broken by simply removing the problem fish for a few days to give the victim time to adjust to the new environment. Once the final batch of fish is in your tank is complete. Congratulations!
This article is part of a series:
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