You are right they are bottom dwellers however the YWG and a few others I have seen do use the "whole " tank .. Not too hard in a nano..
I also had chromis when I first started , and they slept in a lower corner .. Gobies can be provocated to be mean lil buggers ... remaining mostly peaceful . It is possible that he was sick before and the others were protecting themselfs buy knocking him out of "commission" There are sooo many things that could happen that with out video on our tanks 24/7/365 there is no way of "knowing absolutly " what happens ..
My lil yellow watchman that I have in the custom tank has been there for close to 1 year , he will chase the clown across the tank and back again if he seems to get too close .. This past weekend I redid that tank and "rescaped" it I closed off his home and moved some stuff round before he and the clown and shrimp were placed in that calmed him down a bit ...
I can understand the fustrations ! I have been there , and I remember them oh so vividly .... the key here is to never stop learning and never forget what you learn , take everything (including the stuff I write) with a grain of salt .. Believe everything and belive NOTHING .. What works for one may not work for others .. Just because it is something I did or some one else did does not make it right or so ! ..Respect the hobby and it will show you pleasure . Abuse it you will see heartache ..
Slowness by nature in this hobby is what is needed but at times we need to move the speed of light ! It is a balance game , it is a game that most times mother nature will win out on .. Keep learning , keep trying , and dont ever let anyone put ya down or beat yourself up for something that ultmatly we have 0 control over yet have total control !
10 gallon ~6.5 gallon custom