Blue Crayfish almost died last night! And some questions

[mandelyn]

Our fish tank is near the couch, so in the evening is when I look in on it the most. Saw our Blue Crayfish on his back, and thought he was dead! Poke him with a wooden spoon, and his legs moved, so I turned him over and wracked my brain for an answer. I don't know how old he is, we haven't had him long. He's max size, and they only live about 5 years or so from what I've read about them online.

I immediately thought ammonia levels, but not having test strips on hand I had to just do a water change and see.

Then I noticed the flow from the canister filter was weak. So that got taken apart. It was so bogged down with crud in the hoses, not the filter itself. So flushed that all out.

Then gave a thought to oxygen levels... for the past several months I've been keeping the water from the filter below the surface level to reduce noise... part of why I hadn't noticed the reduced flow.

Changed everything around, added a flow pipe with holes in it, and started breaking surface water.

He was so weak I thought he was a goner for sure. This morning he's still alive, slightly more alert, and had moved to the other side of the tank into his cave. So... progress.

Now... crayfish at some point shed their skin for growth. We've had him for about 5 months now and he's never done that.

When will they? Do they ever stop shedding skin when they reach 5-6 inches? How frequently are they supposed to do that? Will they go lethargic before it happens?

The fish never showed any signs of issues... no gasping at the surface or anything. It's a 70 gallon tank, with 2 7 inch gold fish and 3 1 inch sized Mollies. Usually I'm pretty good about water changes, this is the first time I've forgotten for awhile.

I'm thinking it was the water that almost did him in. But this skin shedding thing I don't know anything about. With the gold fish being known to boost ammonia levels, and they crayfish being sensitive to that, I have to stay on it.

Also, when I took the filter apart for a rinse, on the sides I saw this strange white/clear and hard substance, laid out almost like criss-crossing paths from a slug... like what you see on concrete sidewalks after slugs have been all over it. But it was HARD, it wouldn't rub off, I had to scrub it off. I've used canister filters below the tank for several years now and have never seen anything like it. I don't have any snails or anything, and they wouldn't be in the filter anyways. It isn't in the tank at all.

 

[mz.candiz]

My guess is it maybe molting, that can take several hours to a day or so. They will molt their whole life but it slows down alot once they are full grown. They flip on their backs when they molt and they kind of zipper open down their stomach area. He may have gone into his cave to continue the molt as they are quite vulnerable when they go through this process. If you see an exoskeleton soon thats likely why its behaving this way (I usually left them in the tank with my crayfish-it makes a good calcium snack). If no exoskeleton shows up I'd keep an eye on the water chemistry and oxygen levels.

As for the white clear/substance, could it be calcium build-up? I have hard water where I live and if my tank water gets low I will get calcium deposits on my tank walls, and sometimes on filter. But I am not entirely sure from the description if thats what yours might be. If it is you can carefully scape it off with a razorblade, or give it a good scouring with a vinegar dilution.

 

[Gatorpit]

that was my first response too, that he was starting to moult (shed skin). I STILL think that's what was going on. The Moults (by the way) look pretty much exactly like a crayfish, so be sure to look around the tank a bit if you think your crayfish is in fact, dead...you might have just located his skin, and he may be hiding somewhere. Good luck!

 

[mandelyn]

Well he's still alive, though a little slow still. I don't have "two" of them yet, and he hasn't flipped on his back anymore that I've seen. That sounds really neat when they molt though!

 

[hollyk]

That is all fascinating! I don't have any crayfish, but might have to get some....

 

[mandelyn]

She's pretty neat, and a striking blue color. We think it's a she anyways. She can grab small fish fast as lightening, so we make sure everything that lives with her is too big. The large female goldfish got too close once and got pinched. At least goldfish learn. She gets Algae cakes and any fry she can catch for food. The gold fish have spawned before but the crayfish keeps the population in check for me.

 

[Gatorpit]

I've been seeing white and bright red ones at the aquarium stores lately too. I keep thinking about getting one of each, lol.

 

[mandelyn]

They're territorial, so you need several caves and a lot of ground space if you're going to have more than one. I'm used to aggressive fish so my cave building skills has made the crayfish happy. They can climb, so I don't put anything high near the pipes or edges... she's quite... agile. It's neat when a fish pokes her on the tail and she shoots across the tank. She started out super shy but now she seems to know what's what as far as threats go.

They need warm water... so you need a heated tank and tank mates that don't mind the temp.