Stocking Your Saltwater Aquarium

Stocking Your Saltwater Aquarium


Stocking your saltwater aquarium is one of the most exciting times for a marine hobbyist.


Introducing new additions to your colorful marine aquarium to watch and wonder over is awesome fun. For everything to go to plan and your new pets to thrive means that you will need to take things very seriously here in regards to compatibility, stocking levels and choosing healthy specimens.


Incorrect stocking of marine aquariums is a very common mistake.  This usually arises from people moving too fast, picking unhealthy specimens and not doing enough research on their desired pets leading to compatibility issues.


Which leads to stress in your aquarium (mostly the new inhabitants) and even death.


Stocking a marine aquarium is the biggest variable to success in the set up process.  Do it wrong and it can make the whole exercise a disaster, do it right and take your time marine aquarium ownership will be smooth sailing for you.


Any thoughtless purchases at this point can bring compatibility issues later which can be very hard to solve.


The best place to start with stocking is to make a saltwater aquarium plan, and really know what it is you want in terms of marine life.


Start with one or two “must have” species that will be the focal point of your aquarium. This is especially a good idea for small to medium aquariums, with larger aquariums you would go for a type of fish you want such as Tangs, Butterflyfish or Angels.


Once you decide on your favorite fish, find out their exact requirements and set up the aquarium and choose other marine life centred around your tank “stars”.


This keeps stocking very simple and as long as no one fish will compete closely with your favorites for a specific food type that is not readily available you are onto a winning strategy.


Adding invertebrates to the mixture can make things slightly trickier; if you have a fish only with live rock (FOWLR) set up try to use hardier invertebrate species (such as those commonly associated with live rock) that can tolerate a bit more nitrate in the water. This will make your life easier trying to cater to Invertebrate water quality needs.


The key to answering the compatibility question is diligent research on your chosen species in regard to behavior/temperament, diet, size, preferred water conditions (light and water circulation) and growth rates, but ultimately fish have very individual personalities like us people, so it can be common for individuals of the same species to behave slightly differently.


Another factor that affects compatibility is the size of your tank and how much rockwork there is.  Generally the bigger the tank is and the more likely that fish can get out of the line of each others sight for a while the better they will get on.


A good way to ensure new additions settle in well is to rearrange the aquarium (and the residents established territories) when someone new is added.  Keeping a light on at night seems to take the focus off the newcomer and can greatly help with any bullying.


Keeping fish well fed will keep them happy too; a hungry fish is a grumpy fish. When adding new fish to an established aquarium a great strategy is to put about 500mL of display aquarium water into the quarantine tank and visa versa so the newbies and the established fish can become familiar with the scent of each other before they meet. Another good idea is to put the quarantine tank next to the display tank so the fish can see each other.


This brings me to stocking levels; as a general rule of thumb a fish only aquarium should aim for less than 8 inches (20cm) of total fish length (nose to base of tail, not counting tail fin rays) per 22 gallons (100L) of water.


A FOWLR set up with a few invertebrates should have a bit less fish at 6 inches (15cm) per 22 gallons (100L).


Finally a reef set up should have no more than 4 inches (10cm) per 22 gallons (100L).  This is because of the very low tolerances of corals and other invertebrates for slow nitrate build up in the water.


The above estimates allows for room for error, but I warn you if these limits are exceeded by much the bioload will put too much strain on your biological filtration system and all it will take is one lost, dead fish or a bunch of uneaten food over a few days to cause the system to completely crash.


When in doubt under-stock; this allows room for error and also takes into consideration your growing marine life.


When stocking your aquarium start with the more hardy, less aggressive fish first.


This will give your aquarium water valuable time to stabilize after cycling before more sensitive species are introduced and will also help keep more aggressive, territorial species under control if they are not the first additions.


Take the addition of fish very slowly waiting a month or so before adding one or two more, this gives the biological filtration system time to adjust to increasing waste levels.


The final aspect of stocking to get right is choosing healthy specimens.  This can be very easy to do with careful visual inspections of the fish you intend to buy, checking every part of the fish for parasites, disease or other damage.


Make sure the aquarium it is housed in is healthy and clean also. Pay attention to the fish’s behavior to make sure it is acting normally. The golden rule here is to watch it eat (more than once if you can) make sure it has a good appetite, is alert and competitive with the other fish for food.


The final thing you want to avoid is a brand new fish into the store; give it a week or so to see how it adjusts to captive life and copes with the stress of being removed from the reef environment.


It is worth a mention again that where possible buy captive reared marine life, as they are much hardier and happier than their wild-caught relatives. Captive bred species also reduces pressure on species harvested from reef ecosystems, which should be very important to any marine life lover.


So the keys to successful marine life stocking are research, planning and lots of patience. Carefully planned out and executed saltwater aquarium stocking will provide years of happiness for marine life and marine aquarists alike.