Your Cart is Empty
I have perfect parameters, why does my fish die?
The statement below is one commonly seen in online forums and fish groups
"I measure 0ppm Ammonia, 0ppm Nitrites, and low amount of Nitrates, have a pH of 7.0. My parameters are perfect, but I have been losing fish regularly, why?"
Measurable parameters do not fully dictate water quality
While having no measurable ammonia or nitrites can be a good indicator that the tank is properly cycled - that ammonia & nitrites are being digested and oxidized by microbial action, it is by no means the only yardstick of water quality.
Water can measure 0ppm Ammonia and 0ppm Nitrites while still carrying a high load of pathogenic bacteria for example, or be polluted by heavy metals or other forms of organic waste. Organic waste does not convert magically into just ammonia & simple nitrogenous compounds in the snap of a finger.
Take for example, fish food pellets that lay uneaten at the bottom of the fish tank due to excess feeding. Bacteria use the macromolecules (proteins and carbohydrates) present in the animal tissue to grow and multiply and produce chemical byproducts such as ammonia, cadaverine, hydrogen sulfide, and putrescine. In a tank with no filter or a poorly functioning filter, we will notice that it just takes a tiny bit of waste food to cause the water to become cloudy as the microbial population reproduces rapidly to the available food. Depending on the exact microbial mix of the tank, the could lead to a spike in pathogenic bacteria that is harmful to fish health. Having a large amount of organic waste in the tank also consumes a substantial amount of oxygen. In tanks where there is lack of flow or surface agitation, the increased microbial activity can also cause the formation of a bio-film on the water surface, impeding gaseous exchange and dropping oxygen levels in the tank further. All these causes stress to fishes and affect their health - and all this can happen readily in a tank where water parameters test "perfect".
Organic waste levels are easily elevated in tanks that are over-stocked or where the livestock is fed heavily with live-food. For this reason, many professional fish breeders that feed their fish heavily do daily water changes to keep water quality high.
Shrimps and other detritovores are great for breaking down excess food and other larger organic waste particulate matter in the tank.
Having adequate filter media
The filter plays an important function even in planted tanks where the large plant mass can uptake pollutants such as ammonia or nitrates. The volume of filter media needed purely for ammonia oxidation is surprisingly small due to the efficiency of ammonia oxidizing microbes. However, having more filter media than this is important as a greater volume of filter media is needed to polish water to high clarity and capture fine particulate matter.
Ammonia is not the only pollutant in aquarium water. Organic waste give rise to pathogenic microbes if they are not broken down quickly.Thankfully, filter media house microbes that form bio-films that clump even fine organic waste matter and other pollutants together. The filter thus serves as an efficient capture point for organic waste particles as long as there is enough media present. Matured microbial bio-film action is what keeps the water crystal clear in a matured aquarium that has adequate filtration. Even very fine filter media by itself would have a hard time clarifying water without the help of microbial bio-films. Having an adequate amount of filter media is thus important for maintaining good water quality. Cloudy water that is persistent long term is definitely indicative that the amount of filtration in a tank is inadequate. The opposite is also true - having consistently crystal clear water is a good hint that the filter system is working properly with regards to capturing waste organic matter.
Consistently crystal clear water should be the default state of the tank when the filtration system is properly setup.
Substrates, especially soil-based ones such as aquasoil also house a large amount of beneficial bacteria and serve also as an effective capture point for organic debris. Larger size 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. Head 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
