Sorry but this list is horrible
First off engineer gobies will wreck your tank and they get big and mean, sand stars I'm assuming you mean sand sifting stars are also not a good choice for anything smaller than a 6 foot tank that's been establishes for a long time (they starve and die in small tanks) cleaner wrasse? Those guys have a horrible reputation for starving in tanks and they pester fish to death trying to clean them, not to mention the shear size of them and the fact that this tank is too small. Skip crabs go for snails, snails won't kill your fish when they run out of food
Now that that potential train wreck(stock suggestion) is dealt with like everyone else has said ditch one of the clowns, one pair per tank period unless your tank is huge 300+g, second pick either the dottyback or the gramma, dottyback will kill the grama, ditch the puffer unless you're okay with doing all the clean up yourself since puffers will eat or kill your clean up crew (snails, crabs, etc)
Good luck