Yeah besides if they lived in the ocean( by what I have been taught fish can go under 33,660,835 feet with out getting crushed)(wont die under pressure)
You cant really keep more than 2 clownfish of any species in one tank. That is alittle small being less than 20 gallons. It can be done but the harder question is can you handle a such a small saltwater aquarium as in saltwater this is kinda an advanced aquarium as water is affected greater in lower volumes than in large volumes. Which makes a 20 gallon saltwater tank rather hard as you will need to do daily test and adjustments to the water parameters and chemistry.
