Once your saltwater aquarium is fully cycled and the rock fully cured it’s finally time to start stocking it with life. Hopefully you already have in mind at least a general idea of what you want to keep. But regardless of whether you plan on only keeping a few simple fish or a full reef a good first addition is a cleanup crew. This will consist of several varieties of snails, crabs, and other detritivores that will keep algae and detritus buildup at bay. Not only will these critters help finish cleaning up the fresh rock but they are also fairly hardy as well as cheap which makes them and great first addition. On the flip side, snails and hermit crabs aren’t the most exciting of pets. Fish and corals can also be added now, preferably along side a cleanup crew. Just make sure to take it slow. Adding too much at once can overwhelm the filtration. Instead, select one or two of the hardier fish or corals you wish to keep for the first additions.
Unlike freshwater fish, finding a local store that carries saltwater creatures can be a bit of a challenge depending on where you live. Luckily, many reputable online retailers have appeared in the last several years that make it possible to get just about anything. Even so, buying locally is preferable whenever at all possible. Not only is it generally cheaper but also having the ability to check out specimens for possible health problems prior to purchase is a real plus. On that same note, always thoroughly assess any store before purchasing any possible additions for your new aquarium. Look through all their tanks for trouble signs like fish with cloudy eyes or open sores or even large numbers of dead fish and corals. Also check if the store offers any sort of guarantee on the animals they sell. While guarantees are less common on marine creatures some still offer one.
Regardless of what you select and where you get it from, the process from here is essentially the same. First and foremost, turn off the lights on the aquarium and in the room. Bright lighting can be quite stressful to your new addition during the acclimation process. Next place the bag your fish or coral is within in the aquarium and leave it to float there for about 15 minutes to allow the temperature to adjust. You may need to pull some water out of the aquarium to prevent an overflow. While the bag’s temperature is adjusting you can gather some supplies- namely some scissors, some tape, and something to pour aquarium water into the bag such as a measuring cup. A towel and something for waste water can also be helpful. Once the 15 minutes have passed and the temperature has equalized you can cut the bag open and tape it in place along the edge on the tank. Taping it will prevent the bag from slipping into and pouring out in the aquarium.
Even though the temperature has been adjusted there is likely still a difference in salinity between the water in the bag and the water in the aquarium. To address this, you’ll need to slowly add water from the tank into the bag. Start by pouring in enough water to increase the volume in the bag by about 10%. Allow the bag’s inhabitant 5 to 10 minutes to adjust to the new water parameters before adding more water. If you’re acclimating a fish make sure to keep the top of the bag closed to prevent it from jumping out. Continually add more water intermittently until the amount in the bag has about doubled. The bag will probably be getting pretty full by now so drain it back down to it’s starting level and continue the process.
After the bag fills up for a second time it’s finally time to get your new addition into its home. However, we just want the actual animal and not all the water and other crud in the bag that came with it. For fish, carefully net them from the bag and lower them into the tank. Corals and other invertebrates can simply be plucked from the bag by hand and placed into the aquarium. Make sure to handle corals only by the base of their skeleton or any rock their attached to and not their fleshy parts. Finally you can dispose of the water remaining in the bag.
Even once your new additions are in the tank they’re likely still quite stressed from the whole ordeal. Therefore the lights should be left off for the rest of the day to allow them to adjust to their new surroundings. And in particular corals should be placed near the bottom of the tank and left there until they fully open even when the lights are on before moving them higher up the rockwork.
Over the next few days your tank’s new inhabitants should be monitored closely for problems. Any fish with obvious signs of disease need to be removed to prevent the problem from spreading. As for corals, watch for tissue pealing away from the skeleton. At the same time it’s a good idea to begin monitoring the parameters as you did while curing the live rock. If you’ve done everything right up to now they really shouldn’t be a problem. Even so it’s better to be safe than sorry. Should ammonia or one of the other negative parameters begin rising a water change will need to be preformed.
Once your new additions have had a few weeks you can repeat the process for the next creature on your list. The process will be essentially the same with one new thing to consider- bullying. Some fish will begin picking on any new additions as they perceive them as invaders on their territory. To combat this the aggressor can be isolated from the victim for a week or so. A plastic colander suspended at the water’s surface works well for this. Some corals too are capable of causing each other grief by way of stinging tentacles so make sure to not place them too close together. And with that your saltwater aquarium is essentially complete. Congratulations!