Although I'm not new to fishkeeping I have just embarked on a marine setup after 15 years with freshwater. I bought a Red Sea Max (RSM) 130 second hand and can say what a superb tank this has been so far as a first try at the hobby (so easy to set up and maintain). The problem I have as such is the abundant choice of fish to stock the tank. The tank contains approximately 10kg (22 pounds) of live rock and live crushed coral as a substrate. I have two mushroom colonies, a pulse coral on live rock and a devils finger coral on live rock. These corals were donated by a fellow hobbyist from his large marine aquarium. There are also 4 hermit crabs and 4 snails and 1 Yellow coral goby (my wife's choice purely for its stunning colour) and many smaller inhabitants that obviously caught a ride on the live rock and substrate.
Sorry to babble on but the reason for this note is of choice of fish, - can you advise me whether I can have more than 1 type of Clownfish, if so what type, and more than 1 type of Dwarf Angel Fish, again if so what type. All parameters are fine with the salinity 1.024, pH 8.1 and ammonia, nitrite and nitrate all within safe ranges. Any suggestions would be gratefully received regarding other additions as well. Can I add that the customer care at RSM is superb as I had a problem with the timer so when I email them for info they sent me another as a gesture of goodwill. I also had to purchase a new pump and fan kit, which again was sent within a week. Their Customer service is of the highest quality so would recommend this tank to anyone looking to venture into marines.
Small world, as I also have a RSM, the newer 130D, and also like the system and the folks at Red Sea.
And welcome to the marine side of the hobby! As for your questions, because of its size, 30 gallons with a 4 gallon back located sump, only two clownfish of the same species would be advisable. Keep in mind clownfish are quite territorial and will vigorously defend their territory from intruders, even other species of clownfish. Therefore, choose a species, possibly Amphiprion percula or ocellaris and stay with no more than two, as they will call part or most of this small aquarium their 'home.' Purchase two small ones, and as they grow to adulthood will become a male and female that will spawn in the aquarium, as they have in one of my other small aquariums.
As for a dwarf angelfish, it would make a good tankmate in my opinion simply because its just aggressive enough to handle two clownfish without causing undue stress. Furthermore, one of these beauties would round out the number of fish (4 in your tank) that should be placed in a 30 gallon aquarium. One of the following would be a good choice as they are small, easy to feed and note, should be the last added to a small tank - Centropyge acanthops (African Flameback); C. argi (Cherub Angelfish); C. loricula (Flame Angelfish), or C. resplendens (Resplendent Pygmy Angelfish) - difficult to locate, but a beauty.
Hope this helps, and if you need further help in the future, please contact me.