Lateral Line, that was the page I had read
I hadn't realised there were different types until I stumbled across that page, the possibility hadn''t even occured to me, despite having two "side spots" (fish E on that page, though one of my loach has a spot on one side only) My third loach is like picture F. I didn't buy these fish for their different markings, I bought them because I love clown loach
I would have taken whichever the LFS guy caught with the least amount of chasing!
I don't know if they *are* weak stock, let's hope not *touches wood* What I have noticed though, and I had put it down to something else, the side spots are much more retiring than any clown loach in my experience. My third happily swims all over the tank, whereas the side spots will dive for cover if anyone goes near (until lights out). Even then, I can see the largest one parole the front of the tank, looking directly out into the room, before he settles to feed. Quite amusing to watch him do this lol!
When I bought the two side spots, they were in a tank with only other clown loach (and no hiding places) I thought their timidness was down to this, and the fact I only had the pair, so I later bought the third (from a different place). This one was smaller than the first two, and I chose him from a tank that he shared with gourami (he was even trying to feed from the surface like the others lol!) He was much more outgoing, and gradually one of the side spots has started to get a little braver and follow him around. I have had them for about 6 months or so now. I am planning a 540 litre in the next two or three months, I hope to get another two loach and see how an increase in numbers helps their confidence
Also, going by his descriptions on colour variations...my side spots are from Borneo (black pelvic fin, colours not quite as vibrant) My third loach is from Sumatra (red pelvic fin, very distinctive colouring).
Maybe this difference in behaviour is irregardless of markings/breeding, and more to do with the unpredictable nature of this fish, and their previous experiences before I got them. *shrug* Beautiful fish though!