I just wanted to add a point.........the inch of fish per gallon rule is a loosely applied rule. In some cases, it works but you have to take into consideration the size of the adult fish as well as the waste the fish produce. The messier the fish, the less you need to have per gallon. There are cichlids like oscars, for example that although you could fit it into a 10 or 20 gallon tank, chances are it wouldn't be healthy.
Let's see gouramis can get up to 5 inches.........that's about 20 inches.
Dwarf gouramis can get up to 2 inches............that about 4 inches
Synodontis Eupterus can get up to 5.9 inches
Rubbernose pleco can get up to 7.8 inches
clown pleco up to 3.5
Silver tip catfish aka Columbian shark? This is what I found its this it?
Columbian shark profile
If so it gets up to 12-14 inches and needs brackish water as it matures.
Angel can get up to 6 inches.
Ghost shrimp, I have never kept and aren't sure the size, can't seem to find a profile on them. Call it an inch which should be conservative.
Using the inch per gallon, all of these totalled together at full grown size, if the catfish I found is correct, comes to 62.2 inches. That is assuming they all live and thrive and the silver tip doesn't eat the dwarf gouramies as it gets larger.
I don't like the inch per gallon rule, fish have different needs. Most larger fish need more water as they produce more waste. It doesn't take long to foul up water conditions when too much waste is being produced for the amount of water in the tank. Hence, recommendations of larger tanks vs. smaller tanks.
I am not trying to offend you but show you why everyone is telling you your tank has enough fish as it is. Not sure what you did with your clown loaches but they definitely wouldn't fit with what you already have. It is a job to keep fish in good health and when you start overcrowding a tank, you make it that much harder on yourself, as well as your fish. It makes sense that the more fish equals the more waste.
If you want to have cichlids why not check local classifieds, garage sales, etc for used aquariums and equipment. Another tank sounds to me like just what you need and would be happy with.