|All the koi in my pond have a single row of small holes in their scales, one hole per scale, along both sides of the fish. they do seem to have a bit of bloat but no protruding scales and all are active. I have not started to feed as temp too cool. Have you ever seen this and do you have any advice??
You may be describing the lateral line in fish which appears as a row of perforated scales. Each scale in the line descending from head to tail has a single pore or perforation in it. This would be the normal lateral line. The normal layout of the lateral line, as well as the fundamental external anatomy of Koi and Goldfish is found in the images.
(Look it up!)
Most teleost (regular) fish have the lateral line. It is an important "organ" in fish because it has almost "everything to do" with their positioning in the water. The lateral line senses changes in conductivity in the water and are keenly electrosnensitive. In some species, the lateral line also has the ability to "smell" the water. If a fish such as the Mormyrid fishes (Elephant noses) lives in almost constant darkness or the water is traditionally murky in their natural environment, the lateral line may be exaggerated in its function or appearance in order to compensate the limited visual capacity of the fish. Catfish, for example, have tastebuds in their skin and can smell the water with their lateral line. Mormyrids and catfish don't need to see their rivals. THeir lateral line allows them to "feel" their presence.
In other fish, such as the "electric eel" the lateral line not only senses electromagnetic position or fields, it can generate these fields. A good sized South American electric eel can stun a horse or man in the water.