Fish That Can HOLD THEIR OWN?!? (Suggestions...)

[FuriousFish]

So, ive been doing some brainstorming for my 300 gallon... I Would LIKE to have a FEW monsters then a BUNCH of assorted, neat, interesting SMALLER FISH!(3-8 inches...)
My main concern is, i have a 12 inch CLOWN KNIFE...
Heres my full stock list::

1x large TFB (8 inches)
3x Small TFB (3 inches)
2x Small Bala Sharks
2x Large Aratus Cichlids
1x HUGE female red empress
7x WC Creek Chubs
1x Sailfin Pleco
2x Bristlenose Pleco
1x Raphael Catfish

What other small(ish)
Fish Would Go Well In Here??? THAT COULD HOLD THEIR OWN
​MUST BE SOMEWHAT PEACEFUL!!!!!

Also, any BIGGER but PEACEFUL fish would be cool To!!!!!!!!
So, feel free to suggest them to

 

[Tyler2012]

Marbled goby?


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[Drstrangelove]

Haven't kept them but how about Quetzals and Pantano Cichlids? They are supposed to be peaceful. Also the Chocolate cichlid. Just need to be sure to have some lettuce or algae wafers in the diet for the first 2 (which is good for the barbs) and pleco anyway.

 

[Squirtle919]

mangrove jack very peaceful but will hold its own! (jokes...)

id say most basic cichlids would be fine. long as you stay away from umbee/dovii etc

 

[Rafini]

Ptychochromis Oligicanthus. Madagascan cichlid that grows to around 8-10" very peaveful but will fight back when provoked, also they look AWESOME. try searching them on here