Am i fully stocked?

You don't have to buy them paired I had my male long before i purchased the female. Just make sure you can get a real good look at that dorsal fin as that is what determines their sex. It's fairly easy to see the difference

 

barnacle blennies at max get two inches though you could lose one my lfs had in a ten gallon bare bottom QT tank. 3/4" maybe

 

Thanks for the info. I'm going to research this for sure!

 

Tiny and lightning quick! Look them up on YouTube, there are a few vids of them eating. Very cool. Don't have one yet, but def on my short list after goby/shrimp pair.

 

What is a good formula?

 

Not sure what formula to use. I say if you're adding up inches of fish and trying to decide if you can get more, you're probably already at capacity. One thing I've learned from reading so many "am I fully stocked" threads is that 90% of the time yes, they are fully or over stocked.

 

There is no formula. All depends on the type of fish; some do not need much swimming space at all, others will be all over the tank. Of course the adult size of the fish is extremely important.