by Tom Lang
One of the most common requests we receive from our clients is that they want more fish for their aquariums. While we would like to make a sale or see a tank absolutely chock-full of fish of all types and colors, we are often put in the position of having to explain why more fish will require more service. Hopefully this article will explain why this is the case.
We all know that our fish pets produce waste. We just don’t usually see it like we would if we had a cat or a dog or a horse. But think about that for a moment. The larger the animal, the more waste produced requiring cleaning of the litter box, yard or stall. The same goes with quantities – two cats, three dogs and a stable of horses all create more work for us than one individual animal.
All of this might seem obvious, but it is the same with fish in an aquarium. Let’s say you have a good-sized tank with a dozen small to medium-sized fish and things are going along just fine with once-a-month water change, cleaning of the filter, etc., except that you would prefer to see twice the number of fish swimming in the aquarium.
With double the fish, the amount of waste that will need to be processed by the nitrifying bacteria living in your aquarium will be doubled. These bacteria are essential to the success of every aquarium and work to transform fish waste into nitrate through the nitrogen cycle. Nitrate will therefore be produced twice as fast and in twice the quantity when the fish population is doubled. Since nitrate is acidic, an increase in nitrate will cause a more rapid, unsafe drop in pH, endangering the lives of the fish.
Now, taking into account that young, small to medium-sized fish are usually the ones selected to go into a new aquarium, it is important to also consider the potential adult size of these animals. A small fish may stay small if that is the normal size for that particular species, or a small fish may, in a few short months, grow into a large, or even extra-large fish ten to twenty times the size of when it was first introduced.
Rather than focusing on the quantity of fish in an aquarium, it is always more helpful to focus on the total combined mass of all the fish fish within a given tank. We have some clients with one extra-large fish in a medium-sized aquarium and that is truly equal to having twelve to fifteen small fish in that same tank.
The point of all this is that the waste produced by a heavily-stocked aquarium will far exceed what is produced by a lightly-stocked aquarium and will require more water changes, more filter cleanings and more over-all attention to the system. Pushing the limits of what any given tank can support also means that the entire population is close to the tipping point for a tank crash if one or two deaths go unnoticed. Dead fish remaining in an aquarium even for just a few hours can rob enough oxygen from the water to cause all the other fish to die.
Heavily-stocked aquariums require attention multiple times a day accounting for each and every fish, very precise feeding since decomposing extra food can also rob oxygen from the water and scrupulously cleaned filter media and components. Offices that are closed on weekends or over long holidays run the risk of coming in on Monday morning to a tankful of smelly dead fish because it always seems to be that a fish will die on a Friday evening after everyone has gone home.
A light to medium stocking level gives all the fish a much better chance for long-term survival should the inevitable challenges inherent with all aquariums occur. A power outage will not immediately wipe out a lightly-stocked tank. A pump failure will not mean quick death in an aquarium with a dozen fish versus two dozen fish.
We encourage all our clients to stock lightly and succeed with once-a-month service visits. We are always happy to increase service frequency to accommodate medium stocking levels as well. But even with increased service levels, the more fish that are in any given aquarium, the more we need our clients to be partners in accounting for all their fish on a daily basis and to call us immediately if anything out of the ordinary is observed with the fish, the water clarity or the filter system operation before a small issue turns into a major problem.