Thanks all. I too had been thinking how strange it is that there just seems to be one at a time.
I often see increased activity, more noticeable in the Spotties than anything else, after a fairly sizeable water change. They do tend to lurk about in shadier areas compared to
S. lineolata though, so it tends to make observations difficult.
Hels, I'll have to trawl back through the forum and check the gap bewteen these finds. I'll also be checking the filter when I get home (currently in Slough) on Thurs afternoon.
Emma