No that isn't something they can adjust. They NEED to be in groups of 6 or more (8 or more is better). That is just part of their genetics. They need groups. Their social. And they need at least a 20-30 gallon tank.
They will remain stressed and live short lives in that tank.
I recommend setting up a larger tank. It is not suitable for them.
Rule number 1:
do your research BEFORE buying any fish
Rule number 2:
be sure to buy a proper size tank for the fish you want to keep
Rule number 3: be sure your GH is suituable for the fish you want to keep
Rule number 4: buy a tank that suits the type of fish you want to keep...don't buy a tank that suits you...buying a tank too small for the fish you want to keep will result in stressed fish and stunted growth
Rule number 5: be sure tank is properly cycled before adding any fish
Rule number 6: read rule number 1 again!