You Ever Have Crayfish?

[brandoncw]

I recently got two crayfish in my tank. I took the risk of getting these two from a creek in my woods so yes they are wild and yes I ran the risk of introducing disease to my tank and etc. After a week I've had no problems arise so we will see. I don't have to worry about them being to aggressivley hunting any fish in the tank as the are all quite large. I have found one to be very... Constructive if you would. It has been busy digging sand out from under his rock and from what I can tell has made the hole quite large as there is quite a pile out sand outside it. They also seem to be good janitors cleaning up any food missed by the other fish. I find these two pretty unique and enjoyable to watch

 

[Gruntle]

I'd always suggest caution when it comes to crayfish and finned fish. I fear it is inevitable that your cray will one day capture a fish, kill it, and store it in the cave he is building. the fish will rot, and you'll end up with an ammonia spike.
 
Happened to a friend of mine, the water went so cloudy we could not work out what was wrong and ammonia spiked to 8ppm 15 minutes after a 90% water change. The cray had killed a fish equal to its own size and tucked it under some driftwood (right at the bottom of the tank). A very sad end to months of work getting the tank just the way he wanted it, almost every other fish died of ammonia poisoning.

 

[brandoncw]

I'd always suggest caution when it comes to crayfish and finned fish. I fear it is inevitable that your cray will one day capture a fish, kill it, and store it in the cave he is building. the fish will rot, and you'll end up with an ammonia spike.
 
Happened to a friend of mine, the water went so cloudy we could not work out what was wrong and ammonia spiked to 8ppm 15 minutes after a 90% water change. The cray had killed a fish equal to its own size and tucked it under some driftwood (right at the bottom of the tank). A very sad end to months of work getting the tank just the way he wanted it, almost every other fish died of ammonia poisoning.

I'm quite certain the crayfish won't be getting any live meals as he is only 2 inches long and the other much smaller, and the other fish being 8-10 inches and very thick and healthy and could quite honestly eat the cray if it they wanted

 

[NickAu]

The other thing to consider is the stress suffered by the fish knowing there are larger predators in the tank, I think keeping the 2 Crays is ok but consider any fish in the tank they catch food for the Crays ( these are wild Crays and thats how they survive, They don't know aquarium etiquette, or feeding time like those raised in a tank do )  or the Crays are food for something, also look up how to keep then correctly what to feed them and water conditions,
 

 
I have found one to be very... Constructive if you would. It has been busy digging sand out from under his rock and from what I can tell has made the hole quite large as there is quite a pile out sand outside it.

If they are 2 males this could be an issue, Make sure they can both build caves, and forget about scaping your tank, The Crays will do that as they see fit.
 
For example if the water is too hard for them they may have problems molting, While I do not have Crays, I have Red Cherry Shrimp and they are just tiny Crays, and a friend of mine keeps a True Blue Marron: Home in a six foot tank, He just dumped in a bunch of small stones and Monapi wood and the Marron stacked it as it saw fit.