ok first off get rid of the red tail catfish.... cause the suncatfish will be lunch...
And here some info and the sand goby
Common Names: Marbled Sand Goby, Marbled Sleeper Goby
Scientific Name: Oxyeleotris Marmorata
Family: Eleotridae, Sleeper Gobies
Origin: Southeast Asia
Maximum Size: 25 inches/63.5 cm
Care: pH range from 6.5-7.5, Brackish and slightly acidic. Water Quality should be fairly good, but these fish are very hardy, so even though they can survive in semi-bad quality water, ammonia and nitrates still need to be kept low. Marbled Sand Gobies will grow over 25 inches/63.5cm, so a very large tank for them is needed (125-150 Gallon/473-567 liter). The tank needs to have a tight-fitting lid, as these fish are jumpers, and they will try to escape. A large stretch of clear bottom of the tank is need when these fish are fully grown. However, if you raise them in smaller tanks like I did (12-36 Gallon/45-136 liter), they need lots of plants, bogwood, and caves to make them feel secure. Also if you raise them in a smaller tank, be sure to move them into a larger (50-125 Gallon/189-473 liter) tank when they've grown over 6 inches/15 cm. Do not keep these fish in groups, as the dominate will eat the others, and any smaller fish in the tank. Only keep these fish with large fish, such as Bala Sharks, Arowanas, Pacus, and Knifefish. Any fish under 9 inches will be eaten when the Goby is fully grown. Surface Dwellers and fast fish can be kept with these fish, as they are very slow and can't catch anything.
Feeding: Feeding is easy. These fish will eat anything. I give mine krill and feeder shrimp intended for marine fish, and my Goby loves it.
Breeding: Nearly impossible in aquariums as one fish will eat the other, but possibly in a very large tank (1500-2500 Gallon/5678-9463 liter), it could be done.
