Too-frequent molting (long)

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Lisa
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Too-frequent molting (long)

Post by Lisa »

I have a native cray; a bait bucket "leftover" that I believe to be O. immunis (thanks to CanadianCray). He was a little over 1" long when he was given to me on the 29th of May. I say "him" for the sake of simplicity, not because I presume to know its gender. He was temporarily kept in a screened 4g tub with sand and a filter from an established aquarium, plus aeration, and he molted on the first of June. Seemed fine, ate every scrap of his shed exo and was ravenous as always by the time his next feeding was due. Last weekend, I got him a 10g tank and made a sort of "stream bed" in there with sand, flat rocks, river stones and bits of driftwood. Floating hornwort offers shade. The filter and most of the decor came from some of my established (healthy, unmedicated, unsalted) fish tanks, so he didn't have to cycle it, and I tested daily to make sure he was safe. As soon as I put him in, he scuttled between a rock and some driftwood and excavated himself a little lair in there. Driftwood is old and long past leaching tannins.

I read here somewhere that a young cray will overeat and should not get more than one shrimp pellet every day or two, or he may molt prematurely. I don't always feed him shrimp pellets; he gets those, and also Hikari Crab Cuisine, Tetra Repto-Min, algae wafer and spirulina pellets. Treats are frozen krill, mysis, brine shrimp and blood worms and he gets only a little (all are Hikari, guaranteed free of harmful bacteria and parasites). I give him an amount of food approximately equal to half a shrimp pellet daily, a different food each day, and if the mbuna are getting veggies, I give the cray a tiny bit as well. He likes peas and romaine. He has some najas grass and anacharis so he can make himself a salad if he wants, but it appears he prefers to tear it to bits instead (fine with me--even a crayfish needs a hobby. :))

To get to the point of my long story (sorry), in the week he's been in his tank, I haven't seen more than a flash of orange-tipped pincer or a waving antenna sticking out of his lair. I put his food in at night, it's gone in an hour, and since nothing else lives in there, I presume he's eating it. His Highness stalked out to grace me with his presence today, though, and he's considerably larger (guessing close to 1.75"?), so he must have molted again. It's been only ten days since the last time, and although he appears hale and hearty, I fear this is too soon.

- Tank size: 10g
- Temperature: 72F, central air stays on, so he'll be stable and won't get any warmer.
- Filtration: 100 gph, he also has aeration
- Ammonia/nitrite/nitrate - 0/0/<5
- pH/KH/GH: 7.6/8/9 There is a bag of crushed coral in the filter (not sure he needs it, but it seems to help keep my snails' shells strong)
- Cu: 0
- Ca: Don't know, have to order a test, but snails and my crab do well
- Water conditioner: NovAqua and AmQuel (AQ because source water has chloramine, and lots of it)
- Water changes: He's had only one so far because he's been in the tank for just a week, but I change 15% weekly, 20% for critters that are a bit messier. His nitrate was less than 5 ppm, so he got a 15%.

Questions:
- What am I doing wrong to make him molt so often?
- Should I cut back his food to the equivalent of half a shrimp pellet every other day instead of daily?
- Would it be better to give him live snails (ponds/ramshorns, cultured inside) that he can catch, and cut back the feeding of more "concentrated nutrition" foods to a couple of times a week?
- Can he have a live California blackworm as an occasional treat, or would he just chop it up in his efforts to eat it, leaving me with a colony of worms trying to take up residence in the tank?

My sincere thanks to anyone who took the time to read this. I apologise for its length, but if you don't know what I'm doing, you can't tell me what I'm doing wrong, and I want to take good care of this li'l guy.
CrayfishAssociation
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Post by CrayfishAssociation »

Off the top of my head - if you are keeping him with snails, I will assume you may be adding calcium to the water for their shells.

I dont really see any issue with him moulting often, as they do when they are young. I would suggest that the calcium levels in your water are playing a role in just how often it is happening. This is not really a problem and will help with the condition of his exoskeleton and promote successful moults. (the bad ones usually happen in soft water with low disolved oxygen).

A change in temperature will also trigger a moult. This may be a result of not making the change out water the same temp as the tank (just guessing).

Feeding in general works on 2-3% of their body weight every 2 to 3 days, though as fingerlings it is better to have smaller amounts of feed available more often to total the above calculation. Live feed (blood worms work well) does well to help balance his diet if you are not culturing algae.

So, after all that I will put my money on the water changes affecting the water temperature slightly. Everything else you are doing looks to be just fine.

cheers
Paul V
Lisa
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Joined: Fri May 26, 2006 5:13 am

Post by Lisa »

When I do water changes, the change water is within a degree or two of the tank water, so I don't think that could be it unless he's more sensitive than I think. I'd thought I was doing something horribly wrong to cause him to molt so frequently; I didn't know it could be simply because he's young and small. My ghost shrimp (none with the cray, never will be) molt quite often when they're small, but crays seem to have a much more "substantial" exo, so I didn't think they molted so often.

Yes, I do have crushed coral in his filter, but no snails living with him; they are in other tanks. I don't use a liquid calcium supplement, just offer calcium-rich foods. I mentioned the snails only because they need a reasonable amount of calcium or their shells will become pitted and weak, and since I don't have a calcium test, I was using their long-term success as sort of a "guess gauge". I have cultures of feeder pond and ramshorn snails if he'd like those for food, though.

Live food I've got--I'm sure there's a blood worm or two in my daphnia cultures, and I've got baby red wigglers and white worms that he can have as well.

Thanks for your help and for taking the time to read the near-book I wrote!
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