suitable reef safe fish for a 20 gallon

[Delphinus]

Also a scooter blenny doesn't belong in a 20g. They simply do not last long in captivity, the longest I have ever seen or heard of them lasting is about 18 months or so (and usually it's a lot less). Even if they eat prepared foods, they eventually starve unless there is a tremendous supply of live foods offered, way more than anything less than a hundred gallons or more could ever hope to provide, unfortunately.. Sadly, dragonets (scooters, mandarins, psychedelics) LOOK like ideal small tank fish, but they're not.