Coldwater setup

[biggmark]

i use kids play sand in my small axolotl tank looks far nicer than gravel

[chesters1]

why are some of those fish swimming upside down?

those fish are going to be pretty bored! rooting around on the bottom is natural to them ,an underground filter with 4 inches of gravel then a plastic mesh barrier and another 2 inches of slightly larger gravel will filter and still let them act like fish ,you can plumb your outside filter in to the UG filter and it will act as a prefilter saving you cleaning it out as much ,and remember never clean sponge filters in tap water and let top up water rest for a few days (a dustbin is great) before adding it