Fish Health - White Spot

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White Spot

A Koi keeper has 3 main problems apart from KHV:
  1. Ammonia
  2. Columnaris.
  3. White Spot. and this one is linked to the previous two.
White Spot is a stress related infection - no stress no white spot. You don't have to be a brain surgeon to under stand that one.

This problem has a bacteria back up, these symbiotic bacteria live within the protozoan, alphaproteobacteria (rickettsiales), sphingobacteria, and flavobacterium columnare which enters the proazoan via the cilia. As you can see a cocktail of infection. This why white spot is such a killer. When fish have been infected to a high degree no treatment works - they just die.

White Spot is ichthyophtririus or ich as its sometimes known. It is a ciliated protozoan that encysts under the skin of the fish. These encysts gives the disease its name as they look like small white pin heads.

In Koi infection it mostly, but not always, takes place in the gills, and it's the gill mode that is the killer. White Spot on the gills cannot be seen unless it is tested for and so the wrong treatment is often used and the fish does not die with speed.

There is also a problem with this disease known as asymptomatic carriers, which can remain in a pond for an indefinite period until a new fish is added which are immunologically naive to White Spot will contract the disease immediately.

If a fish is introduced to pond containing an endemic ready infected but asymptomatic group of fish and it survives without treatment then it will have the same immunity as the other stock. However, if the new fish cannot resist infection then will show signs of the disease very soon and give the impression you have introduced an infected fish but in fact it's your stock that are at fault.

Damage to the gills is the main way it kills, but also damage to the skin with secondary infections. In fact, unless you have an epidemic, its mainly the secondary infection which kills a fish even though it may have been cured of White Spot..

Immunity will not show its self in quarantined fish. Fish look very ill with White Spot like us having the flu rather than a cold. Most White Spot infections are brought into a pond by new fish either netted poorly or transported in poor conditions.

An outbreak in a pond with no new fish added indicates the system is at fault and needs sorting immediately, before any treatment starts.

When buying fish, if there is one that looks like its was one number of the lottery win, then there's a good change it has white spot.

Do not believe the magazines and books -White Spot can infect in Spring, Summer, Autumn and Winter. I know I've seen infections in mid winter. All the cold water does is slow down the time from encysts cysts to spores and re-infection.

I've already stated I don't give out treatments on this site, but nothing works other than malacite and formalin. I know it will harm your filters, so run a by-pass. You are between the proverbial rock and a hard place. If you don't your fish will die. Use fresh mix not rubbish that's been mixed in bottles when the Titanic went down.

Salt Treatment
I have completed my trails using salt for white spot (ichthyophthirius multifiliis -ick ) including the asymptomatic form. My finding are as follows: The results showed the fish are COMPLETELY free of this - what I consider a fish's premier infection, on a standing with K.H.V, as both will wipe you out.

Treatment now available

The following article is acknowledged with thanks to Doc Johnson of

Freshwater Itch

Freshwater Ich - Ichthyophthirius multifilis - is a killer of very small fish, and can cause "redskin" disease in the winter regardless of fish size.

Look closely at gill tissue under the microscope to be sure to exclude this pathogen, because it does not usually cause the typical "white spot" syndrome as in other fish. Therefore, it's often an overlooked diagnosis. Clears easily with Salt (0.3%) but sometimes takes four to five days because the epidermal phase (explained in the book) is safe from treatment

If I had to guess, I would guess that every singe hobbyist in the whole world WILL encounter Ich at some time. Usually the meeting occurs early on, as a beginner, before water quality parameters such as Ammonia, Nitrites and 'The Cycle' become more familiar, and 'Quarantine' is just a high ideal observed by a few pathetic perfectionists.

What is 'Ich'?

Freshwater Ich (Ichthyophthirius multifilis) is a ciliated protozoan that encysts under the epidermis of the fish; and, in its encysted condition, causes small white spots all over the fishes body and fins. In some cases, Ich spots may be present, but will not be visible. You may still see them under the scope, or you may see them exclusively on the gills. This is how infected fish may get into a tank without being detected, even if quarantined for a period of time. Asymptomatic carriers can sustain a population of Ich in a tank or pond for an indefinite period. Sometimes an owner will purchase a new fish who, being immunologically naive to Ich, will contract the condition immediately upon introduction to an 'endemic' (already infected but asymptomatic) group of fish. If a fish contracts Ich, and survives without treatment, they have shown strong immunity to re-infection, indicating that the potential for a vaccine exists, and is being worked on at University of Georgia and other institutions. It would have astonishing impact on the Catfish industry if it could be achieved.

Ich rapidly kills smaller tropicals and goldfish, while often sparing the larger varieties (fish such as Oscars and Koi). Damage to the gills is the primary way it kills, but damage to the skin with secondary bacterial infection may also figure prominently.
Its life cycle is roughly 2-5 days, but can be longer (5+ weeks!) if the water is cool, much shorter if the water is warmer. There is the old rumour that warm water eradicates it. This is substantially true when temperatures exceed 85 degrees, however; there are strains coming out of Florida and detailed by researchers at University of Florida that can survive and thrive up to NINETY degrees or more! Recall that many of our bread and butter species of tropicals come from Florida, and so may harbour this heat tolerant strain.

The parasite has a phase that encysts in the epidermis of the fish as previously stated (called a theront). It matures under the skin and finally drops off, falling to the bottom (becoming a trophont) to divide into numerous (hundreds) of tiny swarmers (tomites) that actively seek out a host on which to encyst and renew the cycle of infection. Because an important phase of its life cycle occurs on the bottom of the aquarium, it is for this reason that you can help limit infections with water changes made by siphoning the gravel, removing those dividing Ich packets.

Interestingly, some research at Oklahoma has revealed a strain of Ich that does not have to leave the fish and whose Ich packet (trophozoite) remains under the epidermis (safe from medications) and the tomites swarm out under the epidermis. The lesions look much like Carp Pox lesions, being large, flattened, and waxy looking. This parasite is harder to clear because it is the free swimming tomite that we can kill with medicaments.

Prevention is attended at the wholesale level by the maintenance of a 0.3% salt solution which crenates (kills) the emerging tomites. We do not recommend that you as a hobbyist maintain this salt level all the time because live plants can be killed by this, and all species of fish are NOT universally tolerant of this. Still, many have found that salt is a very effective annihilator of Ich infections if normal precautions are observed.