In some respects, keeping fish is just like keeping any other pet. You feed them, you care for them, and to some extent you can even play with them. In other ways, keeping fish is nothing like keeping other animals. In large part, that’s because they are much more sensitive to their environment than we are.
Breathing with Gills
At typical aquarium temperatures, water contains between 7 and 11 parts per million of oxygen. Air, on the other hand, contains about 18% (180,000 parts per million) oxygen. Fish must absorb oxygen from a source much more sparse than what we breathe.
Another difference is that by living in water, fish also swim in their dinner table and their toilet. This aspect goes to the heart of what many new aquarists struggle with, and why so many new hobbyists label themselves “Fish Killers.”
I wrote about the importance of frequent partial water changes last week. While this is good practice, the newly set up aquarium needs more hands-on treatment.
New Tank Syndrome
Fish waste is largely composed of ammonia, and ammonia is very toxic to fish. (This is why they eliminate it from their bodies.) In a mature aquarium, this is rarely an issue because beneficial bacteria converts ammonia into less harmful substances. In a new aquarium, this bacteria takes time to accumulate and grow. In the mean time, toxic levels of ammonia can build up and kill off any fish in the tank.
Cycling a Tank
Encouraging the growth of the beneficial bacteria is called cycling an aquarium. When complete, this forms much of what in nature is called the nitrogen cycle. (The missing parts of the cycle are completed by humans during those partial water changes.)
Three Ways
There are three ways of cycling an aquarium. One uses fish, the other two are fishless.
Placing fish into an immature aquarium will initiate the build-up of ammonia, and it takes time to form bacteria that converts ammonia into nitrite. It could be as long as a few weeks, and in the mean time, dangerous levels of ammonia will accumulate, putting the fish at risk. This is where people generally see the die-off, a few days after the fish arrive. (Sometimes it’s faster, but that is for other reasons and a discussion for another day.)
Because the build-up is toxic, the new aquarist must be diligent enough to change 30 to 50 percent of the water every single day until the cycle is completed.
The second method is to introduce a daily dose of fish food, because fish food decays into ammonia, too. (Old flake food is good for this job.) That allows a tank to cycle without introducing fish to an immature aquarium. That is just good fishkeeping, because animals are not put at risk.
The third method is to add ammonia directly to the tank, but this has its own risks. First, too high a dose can kill a cycle (not allowing the bacteria to gain a beachhead). Another risk is that other chemicals in addition to ammonia may be accidentally introduced to the aquarium–chemicals that will stay there.
Nitrite Stage
Eventually, the ammonia levels begin to fall, and a new chemical called nitrite is produced. This is less harmful to fish than ammonia, but is still toxic. For a cycle with fish, partial water changes are still a daily task.
Nitrate Stage
Finally, after 2 to 6 weeks, a second bacteria colony matures. This bacteria consumes the nitrite and releases nitrate into the water. Nitrate is much less toxic to fish, and a partial water changes twice a week is sufficient to keep the chemical dilute enough not to harm fish. Once the ammonia and nitrite readings are zero, the tank has cycled and it’s ready for a gradual introduction of livestock. Quickly adding population can over-tax the biological filter (bacteria) and cause a mini-cycle until the bacteria can adapt.
How Do I Know?
A test kit is an important tool for the aquarist. There are two major types, test strips and liquid test kits. the strips are very convenient and quick, but this comes at the cost of inaccuracy. Liquid kits take longer, but deliver a more accurate result. Using a test kit is a discussion for another day, but it is a necessity for owning an aquarium. You cannot deal with toxins you do not know are there.
Kickstart
You can give the beneficial bacteria a boost by inserting some filter material, or a decoration, from a healthy aquarium owned by a friend or neighbor. The key word here is healthy. The last thing a new tank needs is a disease vector.
Summary
New Tank Syndrome is really caused by the lack of beneficial bacteria in an aquarium. This bacteria takes time to grow and mature, and in the mean time, toxic levels of ammonia and/or nitrite can accumulate. It is incumbent upon the aquarist to keep the levels of these toxins down to levels survivable by fish in the tank.
