Sad Yorkie

I have been giving a mexican walking fish but it looks very ill, wont eat floats at top of tank, It"s very sad looking at it every day, suffering, I WISH I HAD NEVER GOT IT. Can anyone help........

firstly i suggest you remove him from the tank and place him in a small tub filled with clean dechlorinated water, just enough water to cover his back this will stop him from floating.. if your fridge is between 5-10 degrees pop him in there this will help him destress, make sure you cover the top to stop him escaping. most people cover the pot with something dark to stop the light from startling them.
then i advice you to visit axolotl.org , on there it will tell you evrything you need to know about setting up his tank and keeping him healthy.
its a fair bit of reading but as long as you follow those guidelines you should be ok.
good luck

when you place him in the fridge you also need to make sure you place a bottle of dechlorinated water in the fridge as you will have to do complete daily waterchanges on this container. Use a plastic container with a lid, wrap it in a teatowel, to stop the light flashing/temperature fluctations from normal fridge useage.

While he is in the fridge, you need to test the tankwater for ammonia, nitrite and nitrates. If you don't have test kits for this, take a sample of tankwater to the petshop and ask them to test the water. But do not buy any chemicals to fix the tankwater. If ammonia or nitrite levels are over 0, you do frequent partial (usually 20%-30%) waterchanges on the tank.

Another thing:

1. How large is the tank (measurements please)?
2. What substrate do you have in the tank - ie sand/rocks/pebbles?
3. What temperature is the tankwater?
4. How long have you had the axolotl?
5. Are there any other tank companions?

I'm also assuming you didn't cycle the tank prior to adding him. See: http://www.caudata.org/cc/articles/cyclingEDK.shtml

If you cannot look after him/her I have space and the knowhow to rehome him mate.
Where in the uk are you?