I disagree, I think it looks closer to 5 gal
. Attached is a picture of my 4gal. It's impossible to know how big it is without a brand name and model, or the dimensions
if you knew them we could help better
From what I've seen you'd be better off trying to get a single clown in at the very least a 10g. And if I also remember correctly its better to have them in pairs rather than odd numbers (excluding singular).
A small tank is not the best tank to start out with, as its more prone to temperature changes, waste builds up quicker, and it limits your stocking options etc. Something such as a 20 gallon long would be easier.
If for money/space issues you'd still like to opt with a smaller tank, have a look at gobies. I have almost no experience with saltwater but I'm sure someone more knowledgeable can offer suggestions as to which gobies.