When introducing a new fish to the aquarium, it might not be a good idea to just toss it into the tank after acclimation. Most fish make a bee line for the rocks and often hide for several days, with some never coming out ever again. One way you can add a fish to the tank but always keep them visible is to house them in a separate container that attaches to the top of the aquarium. An acrylic box with a closing lid and multiple holes drilled in the sides to allow for water flow is ideal for introducing new fish because you can easily check up on how they are doing, target feed, and even see how other fish react without running the risk of fin tearing and other related injuries. Keep the fish in the in-tank quarantine setup for a couple of weeks, then open the door one day and let it swim out. Do make sure to also keep a small rock or two in the secluded tank for the fish to hid under.