Crayfish safe to put with other tropical fish

I know this may be a dumb question but is it possible to put a regular crayfish in my tropical tank and how important is it to put substrate? My fish are all healthy and I haven't lost any in the month or so I've had them but I was thinking to get my pH right I would put some plants and substrate in my tank but since I have already got it set up it would be a lot of work so I was just wondering would it be worth putting my fish through the stress of taking them all out for the cycling but any input would help!

 

It's risky to put most crayfish species inside a tank with fish. Eventually, the crayfish will probably kill a fish, or if big enough, a fish will kill the crayfish.

When you say regular crayfish, do you mean a wild-caught specimen, a crayfish from a bait shop, or something else?

 

just a wild caught that has been thru quarantine. I'm thinking I may just keep him as a separate pet.

just a wild caught that has been thru quarantine. I'm thinking I may just keep him as a separate pet.

I was also wondering if I should use substrate and get more plants. I have one type of plant in there and that blue pet store gravel, is it important to get my tank planted. My fish are fine now that's why I wonder if its worth putting them thru the stress while I completely re-do their tank. I am looking to get more fist in the future, any info would be appreciated!

 

How big is your tank and how big are your fish?

 

29 gallon and I have 2 dalmation mollys 3 mollys 3 longfin tetras and 2 swordtails

 

As said before, crayfish will kill anything it catches so you run a chance of whatever fish dying.
I've kept them before but they did best with oscars, which where small, and the crayfish which was big. It just staid under rocks usually. I've considered getting one for my community tabks, maybe a fresh water lobster that has lots of color.