Your Cart is Empty
I have perfect parameters, why are my fish dying?
The following is a common statement on online forums and fish groups
"I am measuring 0ppm ammonia, 0ppm nitrites and low levels of nitrates, have a pH of 7.0. My parameters are perfect, but I am regularly losing fish, why?"
Measurable parameters do not fully dictate water quality
While the absence of measurable ammonia or nitrites can be a good indicator that the tank is cycling properly - that ammonia and nitrites are being broken down and oxidised by microbial action - it is by no means the only measure of water quality.
Water can measure 0ppm ammonia and 0ppm nitrites while still carrying a high load of pathogenic bacteria, for example, or be contaminated with heavy metals or other forms of organic waste. Organic waste does not magically turn into ammonia and simple nitrogen compounds at the drop of a hat.
Take, for example, fish food pellets left uneaten at the bottom of the aquarium due to overfeeding. Bacteria use the macromolecules (proteins and carbohydrates) present in animal tissue to grow and multiply, producing chemical by-products such as ammonia, cadaverine, hydrogen sulphide and putrescine. In a tank with no filter or a poorly functioning filter, we will find that it only takes a tiny amount of waste food to cause the water to become cloudy as the microbial population multiplies rapidly on the available food. Depending on the exact microbial mix in the tank, this could lead to an increase in pathogenic bacteria that is detrimental to fish health. A large amount of organic waste in the tank also consumes a significant amount of oxygen. In tanks where there is a lack of flow or surface agitation, the increased microbial activity can also lead to the formation of a biofilm on the water surface, inhibiting gas exchange and further reducing oxygen levels in the tank. All of this will stress the fish and affect their health - and all of this can easily happen in a tank where the water parameters are "perfect".
Organic waste levels are easily increased in tanks that are overstocked or where there is heavy feeding of live food. For this reason, many professional fishkeepers who feed their fish heavily carry out daily water changes to keep water quality high.
Shrimps and other detritivores are excellent at breaking down excess food and other larger organic waste particles in the tank.
Having adequate filter media
The filter also plays an important role in planted tanks, where the large plant mass can absorb pollutants such as ammonia or nitrates. The volume of filter media required for ammonia oxidation alone is surprisingly small due to the efficiency of the ammonia oxidising microbes. However, it is important to have more filter media than this because a larger volume of filter media is needed to polish the water to high clarity and to capture fine particulates.
Ammonia is not the only contaminant in aquarium water. Organic waste gives rise to pathogenic microbes if it is not broken down quickly. Fortunately, filter media harbor microbes that form bio-films that clump together even fine organic waste and other contaminants. The filter therefore acts as an efficient trap for organic waste particles as long as there is enough media. The mature microbial biofilm action is what keeps the water crystal clear in a mature aquarium with adequate filtration. Even very fine filter media alone would have a hard time clarifying the water without the help of microbial bio-films. An adequate amount of filter media is therefore important for maintaining good water quality. Cloudy water that persists over a long period of time is a clear indication that the amount of filtration in a tank is inadequate. The opposite is also true - consistently crystal clear water is a good indication that the filtration system is working properly to trap organic waste.
Consistently crystal clear water should be the default state of the aquarium when the filtration system is properly set up.
Substrates, especially soil-based ones such as Aquasoil, also provide a large amount of beneficial bacteria and also act as an effective trap for organic debris. Larger gravel, such as pea gravel, suffers from poor surface area and does not work as well.
There are other impact factors for effective filtration, such as having good oxygen levels and adequate flow. Click here to read more in-depth on tank cycling and filtration.
Other fish stress factors
Fish can also face other stress factors even if measured parameters fit their needs perfectly. This includes harassment from other fish, which can be exacerbated by a lack of hiding place/cover, or environmental stresses such as overly strong flow for species that prefer still water. Too small spaces for fish species that need more room to roam can also be stressful. Cumulative stress can result in illness or a reluctance to feed, and lead to deteriorating fish health. Many aspects of the environment can affect fish health besides water parameters.
Where can I find out more?
unlock your true potential
Grow anything, defeat algae, create amazing aquascapes
