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Discussion Starter · #1 ·
This morning, I found my dwarf crayfish lying on its side in the middle of the tank, with its legs twisted and contorted, including one of its pincers bent in an odd way. After 5-6 hours of no change, I used the net to see if it was alive. It jolted away but landed on its side again.

The only change in my tank is that I did a couple of water changes with RO water after I found a couple dead fish in the substrate. Tank is 10 gallons. Inhabitants: 3 dwarf crayfish, 4 cories and formerly 3 guppies (which are now dead).

Tank is established, no ammonia, no nitrites, 15 ppm nitrates.

What do you think is wrong with the cray? It seems like difficulty molting but I am at loss as to why? I would have thought that, now that the water is softer following the RO water change, the molting process would be easier? How can I save my cray?
 

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Hard water help's helps with structural development of the crayfish's Shell (calcium) and molting.
Guppies also do better in hard alkaline water.
Iodide such as that used in marine aquariums at 1/2 dose for marine application, is said to help with molting.
 

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What exact genus/species Crays? Most actually prefer harder water, but there are some dwarf crays that like softer, acidic water.

Do you know your pH, GH, KH, TDS, Temperature?

How long have you had the cray in that tank? Had successful molts before?

Know why the other fish died? Used any meds, if so, what exactly?
 

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Discussion Starter · #4 ·
What exact genus/species Crays? Most actually prefer harder water, but there are some dwarf crays that like softer, acidic water.

Do you know your pH, GH, KH, TDS, Temperature?

How long have you had the cray in that tank? Had successful molts before?

Know why the other fish died? Used any meds, if so, what exactly?
It is a brown colored sibling of the Mexican dwarf cray. It is said to originate around Louisiana and is referred to as Louisiana dwarf cray fish. It sometimes has a blueish tint to it and has been sold as blue dwarf cray by sellers sometimes.

The crays have been in the tank for over a year and a half. They did molt successfully before.

The only difference I have made to the tank is the water change. I believe the guppies died of old age as they were closing in on their 3rd year.

I had a dirted tank setup, so I did not do water changes, only top offs. I now believe the large change in water parameters due to the water change (and with RO water no loss) is the cause.
 
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