Hello. I had another thread but it was for a 75g (HERE it is), fortunately I was able to get something a little bit bigger! 
This tank is 72"x18"x23" (LxWxH)
I have most of it figured out I think, just a few other questions and opinions needed.
I still need help with the schooling fish, which I have a thread for that HERE. I think the decision for that will be made after I'm able to get a list of prices for the fish.
Here was the stocking plan:
1x Brown Ghost Knife
1x Leopard Ctenopoma
1x Angelfish
1x Delhezi Bichir
1x Palmas Palmas Bichir
1x Palmas Beuttikoferi Bichir
6x Schooling Fish
I am wondering now, if I could replace the brown ghost knife with a black one. The black one is my absolute dream fish, and I had originally planned on waiting til we had our own house and I was able to get a 8x4x3 made for it.
The temptation to get it now is very strong and I am wondering if it'd be alright or not. I know on here it has their minimum tank size listed as 75g but..that just doesn't feel right to me. Perhaps 6ft is better though?
If it did get too big for the tank I would hope I could upgrade, but I hate saying that as you never know what will come up. I'd also hope if I couldn't do that maybe I could find someone who had a tank big enough for it.
I was also wondering if I could do a spiny eel..maybe a peacock? Or would it not work well with the bichirs? I'd also like to know if we could add any more bichirs.
I know I am asking a lot and if I had all I want the tank would likely be overstocked, which is why I'm asking ya'll.
..Also also, haha, should I keep the schooling fish at 6 or can I bump them up a bit? I imagine it will depend on which ones I get but want to pose the question anyways.
We have ordered a SunSun HW 304B which is THIS one. Is it okay to have just this one on the tank while the fish are still juveniles? We will add another one later on, or hopefully something even stronger to run alongside it.
The bichirs won't be added in until later either so less stocking for a bit as well. We can run an Aqua-Tech 30-60 on the other side to provide more flow and a little more filtration as well until we get another canister.
I would like to know how big of a heater, or heaters, we'll need for this tank. As well as good places to get them from.
I would like some thoughts on what media to put in it and in what order to place them in. I have spoken to someone who has this exact filter and she uses noodles, MATRIX, and bioballs. She says this allows for better flow as well.
The tank we picked up does not have a lid which obviously we need, so if ya'll know where to get lids for this size tank I'd love to hear it. I found one place but am not sure if it's what we're looking for. HERE it is.
Now for how the tank will look. I plan on black sand, but am not sure on the background. I think a black background would make it a bit too dark especially with the types of fish I'm getting. I want to be able to see them!
Here is my favorite background that I've found, would like to hear thoughts on it: NATURAL MYSTIC.
I have the most beautiful painting ever of what I had planned on the tank to sort of look like. This is very much open for change since I am awful at aquascaping. I know it's hard to recommend plants as we don't know the lighting yet.

The floating plants are amazon frogbit, the big leafed ones between the PVC pipes are banana plants, the fuzzy green on top of the PVC is moss, the plants above the moss would be like behind the PVC and those are water sprite, and the reddish brown plants on each side are red crypts (wendtii?).
And now onto food. I have been recommended Hikari Tropical Sinking Carnivore Pellets for the bichirs. As well as treats of earthworms, black worms, ghost shrimp, and tilapia.
I never did get recommendations for the other fish though, so I would really love to hear some suggestions. I'd also like to know where to buy them, such as petco.
For the treats such as tilapia, can I just get the kind at say wal-mart? Or is there something specific I need to look for?
I believe that's all. Thank you to anyone who reads this and I very much appreciate any and all responses, can't wait to hear from ya'll.

This tank is 72"x18"x23" (LxWxH)
I have most of it figured out I think, just a few other questions and opinions needed.
I still need help with the schooling fish, which I have a thread for that HERE. I think the decision for that will be made after I'm able to get a list of prices for the fish.
Here was the stocking plan:
1x Brown Ghost Knife
1x Leopard Ctenopoma
1x Angelfish
1x Delhezi Bichir
1x Palmas Palmas Bichir
1x Palmas Beuttikoferi Bichir
6x Schooling Fish
I am wondering now, if I could replace the brown ghost knife with a black one. The black one is my absolute dream fish, and I had originally planned on waiting til we had our own house and I was able to get a 8x4x3 made for it.
The temptation to get it now is very strong and I am wondering if it'd be alright or not. I know on here it has their minimum tank size listed as 75g but..that just doesn't feel right to me. Perhaps 6ft is better though?
If it did get too big for the tank I would hope I could upgrade, but I hate saying that as you never know what will come up. I'd also hope if I couldn't do that maybe I could find someone who had a tank big enough for it.
I was also wondering if I could do a spiny eel..maybe a peacock? Or would it not work well with the bichirs? I'd also like to know if we could add any more bichirs.
I know I am asking a lot and if I had all I want the tank would likely be overstocked, which is why I'm asking ya'll.
..Also also, haha, should I keep the schooling fish at 6 or can I bump them up a bit? I imagine it will depend on which ones I get but want to pose the question anyways.
We have ordered a SunSun HW 304B which is THIS one. Is it okay to have just this one on the tank while the fish are still juveniles? We will add another one later on, or hopefully something even stronger to run alongside it.
The bichirs won't be added in until later either so less stocking for a bit as well. We can run an Aqua-Tech 30-60 on the other side to provide more flow and a little more filtration as well until we get another canister.
I would like to know how big of a heater, or heaters, we'll need for this tank. As well as good places to get them from.
I would like some thoughts on what media to put in it and in what order to place them in. I have spoken to someone who has this exact filter and she uses noodles, MATRIX, and bioballs. She says this allows for better flow as well.
The tank we picked up does not have a lid which obviously we need, so if ya'll know where to get lids for this size tank I'd love to hear it. I found one place but am not sure if it's what we're looking for. HERE it is.
Now for how the tank will look. I plan on black sand, but am not sure on the background. I think a black background would make it a bit too dark especially with the types of fish I'm getting. I want to be able to see them!
Here is my favorite background that I've found, would like to hear thoughts on it: NATURAL MYSTIC.
I have the most beautiful painting ever of what I had planned on the tank to sort of look like. This is very much open for change since I am awful at aquascaping. I know it's hard to recommend plants as we don't know the lighting yet.
The floating plants are amazon frogbit, the big leafed ones between the PVC pipes are banana plants, the fuzzy green on top of the PVC is moss, the plants above the moss would be like behind the PVC and those are water sprite, and the reddish brown plants on each side are red crypts (wendtii?).
And now onto food. I have been recommended Hikari Tropical Sinking Carnivore Pellets for the bichirs. As well as treats of earthworms, black worms, ghost shrimp, and tilapia.
I never did get recommendations for the other fish though, so I would really love to hear some suggestions. I'd also like to know where to buy them, such as petco.
For the treats such as tilapia, can I just get the kind at say wal-mart? Or is there something specific I need to look for?
I believe that's all. Thank you to anyone who reads this and I very much appreciate any and all responses, can't wait to hear from ya'll.