What Is Wrong With My Mexican Dwarf Orange Crayfish?

[GoldenRoses]

Hello Everyone,

I'm new to the forum, but not new to fishkeeping. I have 4 healthy tanks at the moment, ranging from 10 to 75 gallons. I'd really appreciate some advice regarding my mexican dwarf orange crayfish though, as I cannot figure out what the issue is!

A little background on the tank and crayfish:

10 gallon tank
Dirt capped with sand as substrate
Moderately planted
Filtered and heated to approximately 78°F
Fully cycled before adding any fish

Current parameters are;
Ammonia: 0 ppm
Nitrite: 0 ppm
Nitrate: 5 ppm
PH: 8.0
*Tested with the API freshwater master test kit*

Inhabitants:
6 female bettas
Started with 3 mexican dwarf crayfish, 1 male and 2 females. But, as I will explain, I only have the 2 females now, and I may even go down to 1.

Here's where my problem started:

I purchased these crays a little less than 3 weeks ago, before the bettas. I had them separate from each other for a few days, to watch their behavior and observe for any signs of illness (during this time I had just added new substrate to the 10 gallon, so it was pretty cloudy). They all looked happy and healthy, readily taking food. While they were still isolated, the largest female (and the largest cray) went through a successful molt. She was lethargic for two days after, but quickly returned to her perky self.

Three days after purchasing them, their tank was finally scaped and ready for inhabitants. I added all three crays at one time, and the smaller female and the male immediately went into a fierce fight. I quickly broke them up, and Luckily no one got injured.

After 4 or so days, I was no longer seeing any fights. All the crayfish had chosen a territory, and only threaten each other if they intrude on the others space.

The bettas were add to the tank a few days later. Of course, they were curious about the crayfish, but they mainly leave each other alone.

For a week, everything in the tank was running smoothly. No casualties, no fighting, and everyone was greedily eating.

Then, my male crayfish started getting sluggish and didn't have much of an appetite. He stayed in hiding more than usual, he was curling his tail, and his colors started to fade. I assumed he was just getting ready to molt. There are plenty of hiding spots in the tank for him, so I kept enticing him to eat until he was ready to molt.

This behavior went on for a week before things took a turn for the worse. One morning, I woke to find the male curled up on his side... out in the middle of the tank. Crayfish instinctively hide when they molt, so I was absolutely shocked when I found him completely exposed. I tried my best to shelter him from the other crays with a small terracotta pot leaned up against the side of the tank.

He stayed this way for 3 whole days. On the third day, it was obvious he wasn't going to wake up. I was absolutely devastated to loose this little guy.

I continued to carefully watch both the girls. The larger female is a pig when it comes to eating, while the smaller one hasn't had much of an appetite.

These past couple days (1 week later), the smaller female hasn't been herself lately. She's showing the same symptoms as my deceased male, and I am extremely worried for her. I noticed her equilibrium seems to be off, taking a closet look it appears that she lost one of her claws!! She must've gotten into a dispute with the larger female, and her small stature didn't give her a chance.

I've been searching everywhere online for an answer. Unfortunately, there isn't much information regarding mexican dwarf crayfish, and diseases they can get. It seems like they are having trouble molting, and for some reason just can't finish the process.

I couldn't stand to loose another crayfish. I've searched everywhere for an answer, but can't find anything! I'm really hoping someone here can shed some light on the situation, and help me save my beloved crays. I apologize for the extremely long post, but I want to make sure you have all the information.

I can attach pictures too, if necessary.

Thank you so much in advance for any help!

 

[stanleo]

Sorry to see this. I had one of these in a similar setup but it was a cherry shrimp tank. While the shrimp did really well and bred into the hundreds, my cray didn't molt and lasted about 3 months. My ph was 6.4. My feeling was that my water was soft and they need hard water. Maybe he didn't have enough calcium and could be the same for you. Just a thought.

 

[GoldenRoses]

Thank you for the reply, Stanleo.

I'm certain my water isn't too soft. I have snails breeding in another tank, and they all have strong, healthy shells. I also offer all of my invertebrates calcium supplements in the form of a homemade gel food, which they all love, so I don't think it's a calcium deficiency, unless they were unwell before I purchased them.

I unfortunately only found one crayfish this morning. The smaller female is nowhere to be found, but I do see pieces of exoskeleton in the tank. I am praying that she's hiding due to an exhausting molt, but I know how vulnerable they are during the molting process, especially with another hungry cray in the tank. Hopefully she turns up intact.

Any ideas as to why my other crayfish passed away? I made sure to acclimate them properly, give them a balanced diet, etc. Could he have acquired something from the shop and introduced it Into the aquarium? Why would one cray be able to easily molt while the others struggled?

 

[GoldenRoses]

Any help?

 

[GoldenRoses]

I did a water change today, and searched every possible nook and crannie. My little female is nowhere to be found.

That leaves me with one crayfish and six bettas, with zero answers. I am completely clueless as to what went wrong, and where to go from here.

Any help would be greatly appreciated.

 

[ChadAT]

Hello, I'm sorry to hear this happened to you. I've been experiencing the exact same symptoms with my little crayfish. He's been like that for about a week now, I've kept him going thus far. I noticed that he started behaving oddly immediately after completing a molt. I think it may be a bacterial infection that got in during the molt. I've added a little calcium to the aquarium to help re-harden his shell. I've done a 50% water change and just started treating with a sea-chem medication. I'll let you know how it turns out. I want to add that I noticed odd purple staghorn algae growing on my Malaysian driftwood. Could be related as it grew in his favorite spot. If you have driftwood I'd look it over. I checked my water and I have no issues. My other fish are all healthy and disease free. Again I'll update you if my treatment works.

 

[raptorrex]

it may just be your Cray's don't like company. illness after a moult is often a sign of a frightened Cray. also putting calcium in the water will not help your Cray's get harder shells. Cray's scavenge calcium from the water and get quite enough at 6.5-7+ph.
I'd try placing your cray in their own tank.

 

[StevenF]

male crayfish started getting sluggish

I have never kept crayfish but I have had shrimp exhibit the same symptoms. In some ways it looked similar to my dad when his thyroid medication is off. Since I am using RO water which needs mineralization to keep the plants alive. I concluded it was a iodine deficiency. I added small amount of iodine tincture (2%iodine) i got at a pharmacy (its a common 1st aid disinfectant).The shrimp immediately recovered. I later got a test kit for iodine and determined a safe dose of one drop per 5 gallons.

he was curling his tail, and his colors started to fade. I assumed he was just getting ready to molt

That diagnosis does sound correct. Have also seen shrimp die do to my water being too soft. That occurred during my first attempt to keep shrimp. I added some sea shells to my tank. They maintain a constant level of calcium and magnesium in the water. Since then I have been successful at keeping shrimp in my tank (no molting casualties). I have also read that excessively hard water can also cause molting problems but I have not seen that.
While they were still isolated, the largest female (and the largest cray) went through a successful molt. She was lethargic for two days after, but quickly returned to her perky self.

While they were still isolated, the largest female (and the largest cray) went through a successful molt. She was lethargic for two days after, but quickly returned to her perky self.

At least in my aquarium any lethargic activity is gone within a few hours of a molt. Also the first visible sign I have of a pending molt is when I cannot find one. I don't see anything in the days prior to a molt. for my 3 inch Singapore flower shrimp, molting a fairly routine thing. They look entirely normal and then disappear, and then later in the day reappear looking and behaving normally. However like I said I have never kept crayfish. Although they are genetically similar to shrimp they may have very different molting behavior.

I would recommend that you get a water hardness test kit. Note if you have plants in your aquarium water harness could drop if your water is soft to begin with and the plants are growing well. Also if you are not cycling water out of the tank sufficiently, water harness could increase. I do a 50% water change once per week.