Fish Facts: Life in a Glass Box

Creating a balanced ecosystem in an aquarium

Rob Homer, Exotic Aquatic, Oakland Park

The basis of all healthy aquariums is what we call biological filtration. This is the presence of good nitrifying bacteria that breaks down raw fish waste (ammonia) into a less toxic form of waste (nitrates). This process begins when fish are introduced into the aquarium. Because the fish are being fed they are producing waste. The nitrogen cycle begins as the invisible good bacteria start to populate the aquarium clinging to all surface areas and feeding on this waste.

It takes an average of four weeks for a freshwater aquarium to go through this process and about six weeks for a salt-water aquarium. Because water conditions are at their worst for this period it is important to start with hardy fish that can endure these conditions and never overfeed or overpopulate the new aquarium.

There is a company marketing a living culture of these bacteria which once introduced take 1-5 days to balance the aquarium. It is refrigerated and has a shelf life of less than 3 months before it expires. There are many other products that can be found on the pet store shelf that claim to cycle an aquarium but in my experience, this is one works really well.

Once an aquarium is established ammonia should never be present again unless the tank is grossly overfed or these good bacteria are over disturbed and killed off by cleaning all surfaces in the aquarium. In general, I recommend a water change every 3-4 weeks using a gravel vacuum to tumble the substrate removing debris and 1/3 of the water, then replace that water with clean, dechlorinated water of the same temperature (never colder) and the appropriate PH.

THE AQUARIUM “CLEAN-UP” CREW

Creating a balanced ecosystem in an aquarium

Meet the aquarium “clean-up” crew, the line-up goes like this: the gang-Brittle starfish, queen conchs, emerald green crabs, blue leg hermit crabs, scarlet red leg hermit crabs, sand sifting starfish, fighting conchs, algae-eating snails, medusa worms, sea cucumbers, and copepods.

We’re talking about reef scavengers who feed on detritus, bacteria, algae, and all other biological waste. These fascinating creatures prevent such waste from polluting the aquarium and literally choking the reef. These animals are generally hardy and relatively long-lived and their benefits to the reef aquarium are immense. By processing the organic waste, which would otherwise settle and rot in your substrate, the detritivores can help maintain chemical balance within the tank.

These fascinating animals are for the most part self-sufficient in the home aquarium, scavenging on the uneaten bits of fish food and waste fallen to the bottom of the tank. A new or very clean tank may not provide enough nutrients, in which case some food should be added about once a week.

On the whole, these animals are hardy and do well even with the beginning hobbyist. Avoid drastic changes in pH and salinity-density by acclimating to new tanks appropriately. Enjoy your “clean-up crew” as they work for you!