I have an orange spot guttata goby and an unidentified pistol shrimp in my 20g. The pistol I have is not a natural host, but luckily they paired. It took them about a week to get together. The shrimp dug a lot at first, but now he has his area and has really calmed down. Any shrimp goby will pair, but you just might have trouble finding the suitable shrimp. Tiger pistols usually do best pairing with gobies.