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Custom High Tech Crayfish Tank

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I have wanted to keep a crayfish since I first saw them in my local fish store over 15 years ago. As soon as I saw one, I was like... WHAT IS THAT?

It didn't help that many fish stores where I live label them as 'lobsters'. Buying one of these guys on an impulse would probably be a terrible idea because they are not friendly tankmates. Plus they do crazy things in a tank like dig giant holes, trenches, move around hardscape, nip fingers and escape anything that doesn't have a good (and heavy) lid. They also eat plants, eat fish, eat snails, eat shrimp, eat anything they can catch.

Soooo a specialized critter.

But I still wanted one!

Since they are such a royal pain, I've never had a tank to put them in. Until now. Recently I had a saltwater build fail to get off the ground. That sucked... a lot. But it provides an opportunity to reuse that tank for something else. And that something is going to be a crayfish!

I am reasonably sure I want what is commonly called an Electric Blue Crayfish (Procambarus alleni). This is a US Native from Florida. I love US Natives for a few reasons so that's a big plus in my book. They are also very easy to breed so getting one captive bred won't be a problem. If I go that route they will look a bit like this fellow right here (not my picture):



There is also the possibility of getting a different kind of crayfish... what kind? Not sure yet. There is a reasonably healthy online community dedicated to crayfish and the USA apparently has a LOT of cool crayfish species. I mean... until recently I've seen only a few crayfish species I know are from the USA. There's the electric blue crayfish, plus a red variety out of Louisiana area called a Red Swamp Crayfish (Procambarus clarkii). And of course the dwarf variety known as a CPO or Orange Mexican Crayfish (Cambarellus patzcuarensis). Then local to me in streams I've seen some brownish ones that are likely Devil Or Common Crayfish (Cambarus diogenes or Cambarus bartonii bartonii respectively) That's about all I knew about. Apparently that's just the tip of rather large and diverse crayfish iceberg.

So I put the word out that I'm interested in captive bred blue native species and we will see if I get any hits on it.

Meanwhile... the tank!

The tank is a weird shape. It's 24 inches x 18 inches x 24 inches tall. It is drilled with a bean animal overflow and two 3/4" returns. Each return has it's own pump in the sump. I also have a UV Sterilizer and a Rex Griggs style CO2 reactor. I currently am using a Red Sea Fleece Roller in the sump but I will likely take that off and sell it and replace it with some foam.

The setup for the tank will basically be a very tall (relatively speaking) hardscape with a cave in the bottom. The cave is for the crayfish, it is not an optional additional either. Crayfish need a place they can molt in and if they can't find one they will try to make one. This is one reason so many people have trouble with them in their tanks. They don't provide good hides and the crayfish are driven to try and dig their own hide and end up destroying a lot of stuff in the process. Or so I've been told.

I am also going to try to grow plants in this tank. Now this one is a bit unorthodox for a crayfish tank. Crayfish eat plants. And even when they don't eat them, they have a tendency to dig them up, cut them up, and generally muck them up. So growing plants is not the norm for a crayfish tank.

I'm going to give it a real go anyway for all the normal reasons we grow plants. BUT I am also going to try to be smart about it. I am going to stick to either really hardy plants or really fast growing ones.

To that end the primary plant in the tank will be Vallisneria Torta. After that I will try a few varieties of anubias, some monte carlo, Hygrophila Pinnatifida, Java Moss, and a plant called Homalomena Insignis which is new to me but the description sounded like a cross between anubias and an amazon sword (not really but that's what it sounded like). All of these were ordered online and should arrive later this week.

My plan is to try a bunch of plants and see what sticks!

The next step then is the hardscape. I cleaned up the tank best I could from my saltwater adventure including removing all the sand. I also filled and emptied the tank a few times to get rid of as much saltwater residue as possible in the plumbing. After that I began playing around with possible designs.

The main feature was always going to be the cave, so the first thing I did was try to construct that.



It honestly came together a lot quicker then I thought it would. So I kept at it, adding in more rock and moving the wood around.



Eventually I ended up with this:



At this point I was ready to start adding sand.

Now a word about my cave. Everything in the tank right now is rock or wood. My plan for the cave was to use small stones to fill in cracks to keep the sand out of the cave. When it was dry, that worked fine.



Unfortionately as soon as I filled the tank with water, the cave filled in with sand from above. Nothing I could do would keep that from happening. So I drained the tank, scraped aside the sand, removed the rock that made up the roof of the cave.





Then I used strips of filter foam I cut for the job and stuffed them around the edges where the sand was getting in, then reassembled the cave.



This time the cave remained a cave, huzzah!

Also somewhere in there I added some small stones/fine aquarium gravel and safe-t-sorb to the sand to give it a more natural and less unform appearance.

I was not entirely happy with it like that. I decided I really wanted the back left corner to be raised up higher so you could see it even when looking at the tank from in front and low down. I added a couple more rocks and more sand. After a night running the tank to clear up the water here is how it looks today:



Overall I am really happy with how the hardscape turned out.

The plan will be going forward to plant the Vallisneria in the back of the tank. Then all other plants to go ontop of the cave/wood with maybe 1 or 2 anubias plants tied to a rock down in front. But otherwise to leave the front of the tank clear of plants so my resident bulldozer can have some space to do his thing. Ideally I will let the plants growout for a month or so before adding my crayfish. So we are still a while away from getting my decapod.

That leads me to tank mates.... and whether I can even have any. Online I see a WIDE variety of responses to this question. Some people say crayfish will murder everything, others say they have a lot of luck with certain fish species etc. So it's not entirely straight forward. I have noticed that small fish species are less likely to be caught and eaten then larger fish species. Some people have had luck with shrimp as well.

To that end I will try some fast moving tiny fish species in this tank. Honestly what I am most excited for is trying some killifish in this tank. I have always wanted to keep some of the more interesting varieties but all my tanks are open topped and killifish generally are fantastic jumpers, so it's never been an option. Given that this tank will need a lid, I think it might be a great opportunity to get one. Assuming of course the crayfish doesn't murder them all to death......... :p

And that brings me up to current. Next time I will hopefully start some plantings!
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Beyond excited to see how that H. pinnatifida grows out. Hopefully you'll let it get a bit crazy so you have a bunch for replanting and such.

Once everything grows in and the moss expands a bit, you'll have plenty of hidey holes for shrimp. A loss of one or two to natural predation shouldn't be too much of a headache. Though, I've found larger crays to be less shrimp and fish hongry than Dwarf CPOs, so you may not lose any.

The tank is tall enough that I'm betting the fish will also be able to stay out of harm's way.
 

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What a great specimen!

somewhat shocked
:unsure:

I guess they transport them with salt?
Some of their wholesalers load their bags up with medication prior to shipment. It's... not my favorite thing.

and some hydrocotyle tripartita
If you're lucky, the cray will develop a tiny appetite for some plants like this that grow quickly. I've never found them to be too plant-hungry, though.

That really is great coloration for a cray that's new to the tank and that's just discovered its main hidey hole.

but here is how they look now:
These are going to be awesome in this tank. Such an underrated fish.
 

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I look at this journal way more than is healthy. Gotta fight the urge. Gotta fight the urge. Can't set up another tank.

What do the brown spots on the H. pinnatifida look like? For me it's always been a plant that needs more CO2 than I usually think I'm comfortable with. But I've mostly been growing it in our gross tap water (4 kH, 12 gH, who knows what else at any given moment) through the years. Seems to also do better for me in tanks where I position it much like you position yours - kind of above everything else. I bet it's just getting broken in and will still adjust a bit more before exploding in the tank.
 

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Its still growing and spreading but its honestly looking worse and worse. Maybe its getting too much fertilizer? Or is my fertilizer really this low of a level?

Here is a picture from this morning when the tanks lights are still off.
Do you know if it was emersed or submerged growth when you got it? Any time I've gotten emersed, I've usually had a majority of it melt. Only the submerged stuff has worked well for me. And part of a tissue culture I got from Petco, of all places - which, honestly, is the best success I've ever had with it. You should check online and at local Petco stores to see what's available to you.

The only special things I do with it are make sure it gets plenty of light - and it is in your tank due to its position - and plenty of potassium. I don't know the exact amount of potassium, but I usually double what I normally put in my dry fert mix. Probably 35-40ppm, if I had to guess. With more CO2 than I like to run, of course. I just don't like to use it on invert tanks. So that's why I say more than I'd like - usually running what most would consider an average CO2 concentration.

Learned the potassium thing here on the forum from an old timer a long time ago. Maybe Diana? Just tried searching for the thread but no luck yet. I think it was in a tank journal, so I'll try to dig deeper later to find it. I've also seen people have better luck when dosing leaner micros. I usually don't add them to any of my tap water tanks or shrimp tanks where I remineralize with Salty Shrimp or my own blend, so I'm not sure if that plays a role.

I'd start by trying to increase potassium to see what happens.
 

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I'll need to buy some potassium then. I am using pps-pro on this tank from Nilocg, so the potassium is mixed in the formula with other macros.

The growth you see in the picture is the new growth since I planted it. The old growth is all gone now. It was doing much better when it was new. It started going down hill before I started remineralizing my water, but I doubt the salty shrimp I've been adding has helped it any. I've been adding enough to get my TDS to between 200-250. I also have some cuttlefish bone floating in the sump, I wonder if that could be causing my issues?
Holes/spots like that could obviously be other issues but potassium is where my gut goes first. Probably the easiest thing to rule out with some dosing, too.

The rest of the parameters don't seem to matter much at all, really, and yours are fine because the moss is doing well. Doubt the cuttlebone is an issue at all.
 

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I'm pretty sure he has gotten a few of the rice fish (as opposed to them dying from other causes) but now that the clown killis have settled in he hasn't gotten any of those.
Isn't it weird how something like killifish can be/seem way more intelligent than something like a rice fish? Always so strange to me that they appear to be smarter than other similarly-sized fish I've kept. The most intelligent-seeming I've had are the types I've had to hatch from eggs in peat and detritus bundles.

Maybe intelligent isn't the right term. But at least in terms of survival, I've almost always found them to be more evolved on the survival front than Endlers, Rasboras, some Tetras. I've had Amanos figure out how to catch Endlers on occasion. But have never seen anything figure out how to catch any sort of killi.
 
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