Depending on the sizes of the fish you probably have some space left. Usually its a gallon for every inch of fish. As long as everyone has a place to hide and swim, you can probably go a few gallons over especially with larger tanks. How big are your fish?
yeah you could put a little more in there, your filters seem good enough, but like fishysmell said, it depends on how big your fish are, and what you want to add.
Gouramis are about 3 inches each. 3 x 4 Gouramis = 12inches
Platties are about 2 inches each. 2 x 2 Platties = 4inches
Serpaie Tetras are about 1 inch each. 1 x 6 Serpae Tetras = 6inches
Sharks are about 2 inches each. 2 x 2 Sharks = 4inches
Clown Loaches are 3 inches each. 3 x 3 Clown Loaches = 9inches
Plecos are 3 inches each. 3 x 2 Plecos = 6
Total is 41 inches. Do the frogs count..??.. because they're 1 inch each. Do Plecos even count since they help get rid of waste?
Yea you got plenty of space. I totally overload my tanks but they are planted and I keep my water in good condition. Plants help a lot. You can go overboard as long as you have low nitrates, plenty of O2, and nobody is picking on other fish. Peaceful fish that swim in different parts of the tank can be kept in higher numbers. It looks like you have plenty of space as long as nothing else you buy swims in the lower third of the tank. Redtails can be killers if they get stressed.
I wouldn't suggest overloading unless you have very hardy fish and they all are very peaceful. It looks as though you could get about 14 more inches of fish to occupy your tank. Don't get happy though. A 5 in. fish does not equal 5, 1 in. fish. I think its safe to say you could go up to 3 in. without addind more gallons. eg. a 3 in. fish requires about 3 gal. a 4 in. fish requires about 5 gal. and a 6 in. fish requires 10+ gal. know what I mean? You also have to compensate for growth and territorial fish. So in the end, your most likely overstocked.