"what's on my fish" ?

Whitespot (Ichthyophthirius Multifiliis),

Although there are a large variety of
different diseases in koi carp, oftentimes symptoms can present in very similar ways, making it difficult to identify the root cause. One symptom, in particular, is white spots on the body, fins, and gills of koi, which tend to appear as a primary symptom in a range of different diseases.

We can’t think of another symptom that confuses more fishkeepers in the hobby, as not only are the white spot diseases visually similar, they are often accompanied by similar sub-symptoms, such as loss of appetite and dulling of the colour.

The best way to identify the cause of your white spot symptoms is to inspect the spots more closely, as although they can be very similar on the first inspection, most spots will have slight variations in appearance.

For example, in cases of Ich, the white spots would be very small, tough, and evenly distributed

(not clumping) across the body of the fish. However, in cases of pox, the white spots may be larger, softer, and may clump together in random patterns and groups.

Identifying the differences in appearance and observing how the spots spread are the easiest ways to distinguish between diseases in the early stages.

Whitespot (Ich) Symptoms:

White spots that resemble grains of sand

Itching or rubbing against the pond

Less interest in feeding

Shyness and swimming alone
Hiding under shelters

Lack of colour & a dull appearance

One of the more common causes of white spot symptoms in koi is the parasite Ichthyophthirius Multifiliis, or “ich”, for short. This stubborn parasite is a particular nuisance for both fresh water and saltwater fish and can be difficult to treat due to its very rapid life cycle.

Ich presents as small white spots on the body, scales, fins, and gills of fish, which can eventually grow in number to resemble grains of sand.

The small spots are the parasite itself, feeding on the fluids contained in the top layers of skin tissue. This stage in its life-cycle is known as its encysted stage, and during this period it’s protected from treatment with a hard outer shell.

Although not initially dangerous, the parasite becomes a huge problem if left to spread, as its reproduction cycle is extremely aggressive, and it can very quickly take over an entire pond.

Mortality rates are high when ich is allowed to spread to other parts of the fish, particularly the gills, where the damage to tissue leads to respiratory problems and secondary infections.

Small white spots that look similar to grains of sand are a tell-tale sign of ich, but your fish may also have other symptoms, such as a loss of appetite, rubbing behaviour, or hiding away from the rest of the fish. Common symptoms of Ich are below:-

How to Manage Whitespot (Ich)
Being an ectoparasite (external), ich should be easy to treat, but theproblem is ich’s rapid life stages and the fact you can only treat the parasite while it’s seeking new hosts. During its white spot cyst stage, the parasites are protected within their hardened outer shell.

However, to reproduce the parasite needs to leave the host and enter a reproductive stage, which then creates more free-swimming infectious parasites. During this stage in the parasite’s life cycle, it can be treated, and it can also be sped up by increasing water temperature. The ich parasite’s life cycle is highly dependent on the surrounding water temperature, with higher temperatures increasing the rate of reproduction.

Without treatment, this would be very undesirable, but if you’re looking to kill the parasite, heating your water simply encourages the parasite into its more vulnerable state so it can be killed much faster.

Water changes help increase treatment effectiveness and also reduce parasite numbers, so are highly recommended.

External antibacterial medicines can also be supplemented to prevent secondary infections from occurring from open sores after the parasite has left the scales.

Above: Whitespot Life Cycle