How many fish for a 20 gallon long.

[Echo2656]

So i was planning to put
a pair of mocha storm clownfish
1 firefish
1 royal gramma
1 tailspot blenny
1 captive bred mandarin dragonet
is that too many fish for a 20 gallon long? If so, how many should i keep in it? How do you measure how many you can have in a tank? Thanks.

 

[Lavey29]

20 gallon with rock scape becomes 14 gallons which is good for maybe 2 or 3 small fish.