The other day, lacking the motivation to do anything else, I was thumbing through some of the many catalogs that I receive from various Water Feature supply distributors. Although I have done this many times in the past, this particular time, for some reason, I was struck by the vast array of chemical treatments on the market for both altering water chemistry to maintain quality, and medicinal products for treating every conceivable curable fish health problem with the exception of, maybe, a runny nose. (Do fish have runny noses?...... How would you know?)
The primary target fish specie for the vast majority of these products is Koi, (Cyprinus carpio, Nishikigoi, Carp).
Are these aquatic creatures that some literally fawn over, these Living Jewels, really that fragile and susceptible to parasitism and infectious disease as we would, subconsciously, be led to believe? I think not!
Koi are a decorative variety of the Common Carp. It is not a separate species. This is evident in the fact that, when Koi are allowed to spawn without any external selection (culling), they will, over time, invariably revert to the black coloration of the Common Carp. A true separate species would be genetically stable.
It therefore follows that we only need to look at the physiology of the common Carp when left to it’s own natural devices in determining the natural sturdiness of the specie.
Carp are usually found in still or slowly flowing waters, lakes and permanent wetlands, commonly with silt bottoms (Environment ACT Undated).They have a greater tolerance of low oxygen levels, pollutants and turbidity than most native fish, and are often associated with degraded habitats, including stagnant waters (NSW Department of Primary Industries 2005). They are most abundant in streams enriched with sewage or substantial runoff from agricultural land and are rarer in clear, cold waters and streams of high gradient. In fact, they are cultured in rural southern Asia in rice fields, which are reported to be the richest habitats of aquatic organisms (Saikia & Das 2009).
Doesn’t sound like a fish that requires pampering, does it? No Wuss fish here!
So exactly what are the water chemistry tolerances that Koi can adapt to? This will be explored in the next post.
