Both these puffers are brackish although the spotted puffers require more salt in the water than the figure eights.
Do not mix the two as they are not compatible. First you need to have a fully cycled tank to keep puffers in, then, if the fish store keeps them in freshwater ( which they can manage to survive in but is not good long term), you need to start your tank fresh and slowly increase the salinity levels.
If they are kept in brackish already then match your salinity level to their using a hydrometer. You can vary the salinity a little from time to time so it doesn`t need to be exact.
Figure eights have great personalities, some get on well, whilst others can be aggresive. It is often best to keep an odd number in a tank, either 3 or 5 in your case. Provide plenty of plants for them to eat, so you will have to replace them every so often, and a few ornaments in the middle of the tank. That will break the line of view if they chase eachother.
Feed a varied diet of bloodworms, snails, small pieces of prawn, cockle and mussel etc.
They become very tame if you spend time with them and are great little characters.
Hope this helps.
Clare
