He was looking a little 'itchy', some minor darting and bumping into things.
And some minor lethargy when he wasn't doing that.
But he was eating well the whole time though, and I noticed him looking a little 'dusty' but I really had trouble figuring out if that was the light playing tricks or what. Under intense light he looked slightly dusty but in normal light he looked fine.
To be safe I did the above, as I was worried about him getting 'velvet' or just generally getting covered in gunk/algae. I have another post in the disease forum.
He seems well today, no more erratic behaviour. But I will monitor him closely. And I found an anti-parasitic recipe that was created by a breeder with over 20years experience so I will implement that as well just to be safe, because its so easy to do and apparently quite effective.