Actually in a 2.5 gal
, you could get away with something like a neon or sharknose goby. The body profile is quite small and will not be cramped for a single fish but no more.
In my 5 gal
I have a green encrusting gorg, toadstools, zoo's, shrooms
& GPS. All doing well. I am a bit lazy with the chem checks on the smaller tanks so I have not attempted scleractinians as yet. I intend to add at least one non-branching LPS
species soon to see how it fairs but I think lightwise they would do fine. Xenia would require you to maintain the chem much closer than with soft corals only but as long as you're willing to do that, it should be fine as well. The only caution would be their aggressive growth rates. It could end up smothering alot eventually so be mindful and frag