Additional fish?

[Idealconcepts]

I will be transferring the current fish I have in my 135gal FW tank into a 300gal FW (8ftLx2ftDx2.5ftH), as soon as it has cycled, and wanted to get opinions on adding approximately 6 to 10 inch expensive smaller fish that school. The reason for this thought is I would like to see some variety in the number of similar fish I have in the tank. The current fish I have are mainly American Cichlids, which are all about 1.5 to 3.5 inches: 2 marble Oscars, 2 Jack D., 2 Green Terrors, 2 Fire mouths, 3 Tin Foil barbs, 1 common algae eater, and 1 common catfish, and also a baby Silver Arrowana that will be placed in the 300 gal as soon as it is large enough to hold its own. Using the 1 inch per fish thing, I have come up with the estimate of 176 inches of fish when my current fish are full grown. Logically, in my mind, I believe I have enough room for the current fish I have, but I’m assuming the aggression level of each individual fish will actually determine that. My idea, and it is only and idea in which I would like feedback and suggestions on, is adding 6-10 fish that grow to a size of approximately 3 to 4 inches (inexpensive in case they become snacks for the other fish). This would raise my total count to approximately 206 (for 10x3 inch) or 216 (for 10x4 inch). I understand these fish might be on the small side and could be potential food sources once the Arrowana reaches the 25-30inch mark and the other cichlids become larger. I haven’t done much research yet on what types of fish I could look into placing into the 300gal, but I did have tiger barbs and they were pretty fast active fish that I have read reach up to 3 inches in length, this might be a little on the small side though. I also thought of Silver Dollars, but read they can get up to 6 inches, so maybe only 6 or 7 of them would be the max to put in the 300gal. There should not be a problem with the bio load as the 300gal comes with a wet/dry and two pumps rated at approximately 1,100 or 1,200 gph. Can I get peoples opinion on either adding the Tiger Barbs, Silver Dollars, or other fish that would have a chance of surviving in the 300gal tank, and how many would you recommend for each (Tiger Barbs, Silver Dollars, or other fish). Thanks in advance for your comments.