if i could go goby/shrimp and then another 2 small fish, why not 3 small chromis?
Yes, its very well covered, I know gobies like to jump ship, as do many fish
oh and do gobies need shrimp? I would certainly provide a shrimp and a goby to complete the pair either way, but im wondering if the relationship is absolutely nessecaryor just a luxury for them both
Because the goby/shrimp has very different habits from the chromis. Gobies don't move around much. They have a territory and tend stay there. 3 chromis, on the other hand, are social fish that need space to swim. They also employ a pecking order. This isn't great in small tanks. In a big tank, you can have more numbers and the fish that's lowest in the pecking order has space to break from the group to just go chill. In a small tank with less fish, the bottom of the pecking order has no where to go. So, when you have little tanks like you and I do, it's good to get 2-3 fish with similar social habits, but contrasting behavior, and that do best alone. See, in my 8g I've got...
Royal gramma - prefers to be solitary or in mated pairs, likes a cave to retreat too but swims in the water column. Territorial to fish that look like it but basically peaceful.
Yellow watchman goby - prefers to be solitary or in mated pairs, burrows, dwells in the bottom. Territorial to other yellow watchmans but basically peaceful.
So these two fish have a similar profile. They both don't mind being solitary, but they don't look anything alike and they don't go to the same parts of the tank. It works. That's why having 2-3 fish work in my case and why it doesn't work with chromis. Does this make any sense?
Also, regarding the shrimp/goby pair. The shrimp needs the goby more than the goby needs the shrimp, IMO. But in all fairness, the shrimp really doesn't add much to the overall bioload of the tank, and to watch the group together is fascinating and well worth the investment. My pistol was originally paired with two Yashas, but they jumped (I hate yashas now ), and actually had to be alone for a few weeks. Terrible time for him. He never came out. I only knew he was alive because he would click his claw. Now, that he has his goby, he comes out and cleans and gets food for the goby and is a much happier shrimp, I think. I was rewarded with a shed the other day, so I know now he's growing. And my goby has grown too. Good ol' Tigger & Eeyore.