can I have these in the same tank
 

right now i have a 55 gallon with 7 red zebra cichlids and 2 crawfish and i getting bored of all the cichlids hiding in rocks and the only time I get to see them is when I feed them and then they go right back into there rocks. so what I'm wandering is can I put a tire track eel and a Cuvier Bichir they will be small at first but I'm really worried that they will get eaten by my crawfish or my largest cichlid and he is about 3 1/2 inches long but i do have a smaller tank that I could put them both in until they get big enough

The crab will almost certainly eat them. I'm concerned that both the eel and the bichir will get too large for your tank, also both of them tend to hid alot as well. They may not be what you really want.

okay
 

the place I'm ordering them from says that the eel needs a 50 gallon and the Bichir needs a 90 but i read on them and other ones need 55 gallons when they grow larger than the one that i want so what size tank do u think that i would need because I'm thinking about getting a 125 gallon soon but I'm not sure if i want fresh or saltwater

Please don't order difficult fish until you first know what you want down the road, and you have the tank to accomodate the fish at maturity. Anything less is cruel to the fish, and it will at best be unhealthy and at worst likely short lived.