• Blackening / developing black patches
• Red patches developing
• Yellow areas developing in the red of my Gosanke
• Tiny black pinheads in the skin (Shimi)

Blackening / developing black patches
Fish may develop a blackened area or areas for numerous resons, but here is a partial list:

1. It's normal development of Sumi (black) color

2. Fluke infestation causing damage to the skin.

3. Other parasitism also causing damage to the skin

4. Ammonia burns

5. Chronic Chlorine exposure (Failure to dechlorinate)

6. Formalin overdose is also caustic trauma to the skin.

7. pH crash non diagnosed

8. Trauma from nets

9. trauma from other fish

10. Neascus, very very rare.

If there is something in the history that supports the caustic chemical theory, go with it.

If there is not, and water seems fine, perhaps a salt treatment to 0.3% is in order.

The blackening of the fish is related to a healing process. In these lower vertebrates, healing occurs by the creation of new epidermal, or scar tissue. The leukines that call up the healing tissue cells are rather non specific, unlike we as higher vertebrates. So, when the fish goes to healing, we may see the ingress of Melanophores, or black cells as well as new epidermal and fibroblastic cells. These melanophores stay around for a few weeks until they relaize they were not really called for, then they go away.

A great case example, which is quite common, is when fish are burned by Ammonia, or they are overrun by Flukes. Once the water quality is restored, or the flukes are eliminated - the fish can heal and a sudden blackening may be noted.

In general, blackening of scales is a healing symptom. A good thing. You just got to wonder what they are healing from? Sometimes you never know.

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Red patches developing
If you have red patches forming in the fish, this is covered better in the "body" discussions of the fish. Click here to go there.

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Yellow areas developing in the red of my Gosanke
You could be seeing yellow areas in the reds of any type of fish, including Kohaku, Goshiki, Tancho Gosanke or any other fish with bold, solid reds. More highly bred fish from the best breeders are the most likely to develop this problem. This is a condition called Hukkui. I am unsure if I am spelling it exactly right but we have shown in biopsies that the condition is a "Lymphocytic / plasmacytic infiltration most consistent with sunburn." However sun is not necessarily a player in this condition as it has been developed and found in Gosanke which were kept for years exclusively indoors. I personally believe that Hukkui is a genetic instability in the chromatophores of the red pigmented epithelium, which are destabilized by chronic background pollution levels, instability in the pH and other irritating factors in water quality.

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Tiny black pinheads in the skin (Shimi)
Shimi is the development of tiny black pinheads in the skin (especially but no limited to) the reds on Gosanke. It's a harmless change but it is economically devastating to the value of the fish - because it makes the Kohaku into the world's worst Sanke. Shimi spots can be removed surgically and are unlikely to come back in that specific area. The Shimi spot only exists in the suprficial epithelium so no sclaes need to be removed in the correction of Shimi defect. I asked some breeders about the Shimi and they said it was genetic instability. They added that it usually doesn't happen in purer, longer bloodlines of fish. I am unsure if this is 100% true, and they added that chronic poor water quality can precipitate the appearance of the condition. It is also anecdotally believed that while harder water (higher calcium and magnesium) levels enhances the Sumi (desirable black pigment pattern) in the fish, it also potentiates the development of Shimi in fish which are not supposed to have any black.

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