"Big" fish suitable for this tank

[Khuligirl93]

Maybe some opaline or pearl gouramis?

 

[Luananeko]

Opaline, Pearl, Blue, Gold, Lavender, or Platinum Gourami would all fit well as "big" peaceful fish. If you go with more than one I'd recommend sticking to females though. The males tend to disrupt the peace quite a bit, especially if you want to mix types.

Otherwise, I second the rams suggestion. They have wonderful personalities and color, and typically don't bother anyone else much unless they're breeding.

A single Red Tail Black Shark is possible too, but they tend to turn into jerks as they mature. Not jerks as in they'll kill everyone (well, usually not), but jerks in that they chase everyone around enough that the other fish may get stressed. 75 gallon is big enough you should be ok, but I still have to re-arrange the tank occasionally when my RTS female gets a bit too pushy. If you go with the rams you especially will have to watch the RTS carefully, as they can stress the rams to death depending on the personalities of your rams and shark.

 

[Sidman24]

Opaline, Pearl, Blue, Gold, Lavender, or Platinum Gourami would all fit well as "big" peaceful fish. If you go with more than one I'd recommend sticking to females though. The males tend to disrupt the peace quite a bit, especially if you want to mix types. Otherwise, I second the rams suggestion. They have wonderful personalities and color, and typically don't bother anyone else much unless they're breeding. A single Red Tail Black Shark is possible too, but they tend to turn into jerks as they mature. Not jerks as in they'll kill everyone (well, usually not), but jerks in that they chase everyone around enough that the other fish may get stressed. 75 gallon is big enough you should be ok, but I still have to re-arrange the tank occasionally when my RTS female gets a bit too pushy. If you go with the rams you especially will have to watch the RTS carefully, as they can stress the rams to death depending on the personalities of your rams and shark.

Best way to tell sex of gouramis ?? I had a blue one once and he picked on my other fish. I think pearl and oplane are nice looking

 

[Luananeko]

It's kinda tricky to describe, but once you know what to look for it's pretty easy. The dorsal fins on the girls are shorter and rounder, while the males have longer, pointed dorsals. On pearls, the males will also have red on their chest and depending how old they are they'll also have extra fringe trailing from their lower fins.

Here's some pics I was able to find...
General female signs (this ones a three-spot morph of some sort):

Pearl gourami (female top, male bottom):

You can see a slightly exaggerated bit of what I mean by the pointy dorsal fin on the male pearl there too. Opalines aren't quite so obvious, but the same basic principle applies. If you mix pearls and opalines, get girls only and at least 5-6 total so the pearl doesn't get bullied too much. Opalines are decidedly more feisty.

 

[Bichir Bro]

Male pearls generally have longer and more flowing fins and like previously stated they do have much more red in their chests. Pearl gouramis are my favorite gouramis.

 

[Sidman24]

It's kinda tricky to describe, but once you know what to look for it's pretty easy. The dorsal fins on the girls are shorter and rounder, while the males have longer, pointed dorsals. On pearls, the males will also have red on their chest and depending how old they are they'll also have extra fringe trailing from their lower fins. Here's some pics I was able to find... General female signs (this ones a three-spot morph of some sort): Pearl gourami (female top, male bottom): You can see a slightly exaggerated bit of what I mean by the pointy dorsal fin on the male pearl there too. Opalines aren't quite so obvious, but the same basic principle applies. If you mix pearls and opalines, get girls only and at least 5-6 total so the pearl doesn't get bullied too much. Opalines are decidedly more feisty.

Thanks so much for taking the time to help me!