Straight to the point - why do my fish flick against the sand?
I've had this issue on and off since I've had this tank (Fluval Roma 125, Oase Biomaster Thermo 250, sand, spider wood and some aquarium pebbles in the tank). 8 zebra danios and five platy. Temp of 22 degrees.
Originally had a Fluval U3 in the tank but when we moved house I decided to go for an external. I had major trouble cycling the tank but eventually we got there. I've had flicking issues for as long as I can remember, though it's only happened twice since running the external (once when I fed frozen bloodworm, and now about half an hour ago. I checked water parameters and ammonia seems to be at 0.25ppm - WHY?
I'm getting fed up with this happening - part of the reason I went for the canister filter is that there should be more beneficial bacteria in there so I thought it would be the solution.
Can only reply briefly - apologies. One thought - does your water company use chloramine in your tapwater, and are you using a dechlorinator that addresses that (as opposed to simply addressing chlorine)? Test your tap water for ammonia as that might give an indication.
I wouldn't worry about a reading of 0.25 as the API test often reads that when it's truly at 0. As for the flicking, well fish do that from time to time and as long as it's not getting worse I would put it down to a bit of irritation from sand or similar.
Perhaps I did get a bit carried away but to me it can't be a coincidence that I see one of the danio flicking then when I test for ammonia it reads 0.25ppm. I'll keep an eye on them and hopefully there is no issue.
As you're using Seachem Prime, any chloramine in the water from the water company (and which may show up as ammonia/ammonium on test kits) will be taken care of by the Seachem Prime, so you can relax on that one.
Does your ammonia register as 0 at all other times?