Taken from another post i made a while ago about "freshwater" pipe fish
There are many species of pipe fish that live in brackish and even freshwater but only two appear in shops with any regularity Enneacampus asorgii the African pipe fish and Microphis brachyurus aculeatus sometimes called the giant African pipefish. Both are brackish fish which need a SG of around 1.010 to be comfortable and are very sensative to changes in water chemistry, they should only be kept in large mature tanks with stable water parameters and low nitrate levels. The problems come with feeding pipe fish, they will only accept very small live foods and will quickly starve to death without them, many are already too far gone before purchase since the lfs no litle about them or their feeding habbits. The best foods for small specimins are fresh hatched brineshrimp and daphnia or other tiny crustaceans like cyclops, larger specimins may be able to take bloodworms, glass worms, adult brineshrimp and daphnia and even new born guppy fry. They are best kept in a species only tank or with just a few small non aggressive tankmates like bumblebee gobies.