Antony
Fish Fanatic
Are you sure you can keep her in a better condition than the shop? Do you know of anyone else that could take her from you?
In future, don't buy fish just because they are being nipped or look ill. 9 times out of 10 people do this and can't provide better conditions for the fish themselves.
If you really can't find another member on here for example who is willing to take her off your hands, then you need to make sure your tank is properly cycled. Do a test and post your readings on here. Then add some media from your other tank into the filter of the 20L to help with processing ammonia if your filter isn't already cycled. You will need to keep her alone in the 20L and make sure there are plenty of plants, hiding places and things to stimulate her. Dwarf puffers are extremely intelligent fish and need to be kept entertained or they can get stressed and ill very quickly. You need to perform frequent water changes to ensure that the water quality stays at it's optimum. I'd recommend 50% every other day to begin with, maybe more if you have any ammonia issues.
i would gues shes in better conditions atm seems as shes still alive and healthier than when purchased so life saved so far ...not that i have ever lost a fish touch wood.
the large filter from my 90l is working on the 20l atm to speed up the process a little whilst a stingray filter fills its place in the community . Im thinking of pretty much 75% of the floor being coated java moss a load of ferns some xmas moss and a rock cave or 2 plus a bubble wall an thats about it? .....anything i missed?