Blue Crab Keeping Journal (Callinectes sapidus)

[myllkti]

So many who see this will be like “no you shouldn’t have gotten a blue crab!” but i hope you can understand how a young child I have limited authority over (my brother) may have impulsively decided to keep this crab, as many of you have similar stories of getting into hermit crabs. If it helps, he has done research with the limited resources available and has learnt his lesson. Anyways, I’m hoping to keep a little journal of our blue crab care journey here in case it helps anyone else, or in case anyone else can help us (there are like no resources on this urgh!)

To start off, we’ve heard people struggle to raise them well in 90-120 gals. Our only available tank when we first brought it home was a 10 gal. It has survived in it for at least a month now. My grandpa insisted it only be given enough water to keep its gills wet (it can survive up to 48 hr out of water as long as gills are wet, undisputed afaik), but upon urging by those who happened to know a tad about blue crabs we submerged it by an inch or two. This seemed to be the right decision as two nights ago, June 18, it molted and yesterday, June 19 was hardened enough to eat in the evening. Today, after giving it another night to harden, we changed its water and also added a bunch now that we know for sure it can be submerged, so that any ammonia would be more diluted and more oxygen would be available (we do have an air stone Aka bubbler so the oxygen levels aren’t that bad or anything, just more is better, and a positive side effect). It is about 2/3 filled now (we only hesitate to fill it more because it would swim up and potentially escape as our lid is not super secure atm.

We feed it 3 meals with only one or two bites each meal. We absolutely can not find info on how much nor how often to feed so that seems a nice moderate test schedule for us. It gets mostly krill, sometimes chicken (not exactly something from the see but it’s a scavenger and it loves chicken so maybe?), every once in a while brine shrimp (messy), and as a rare snack some broccoli.

We heard it produces much waste and by jolly does it. The 10 gal lasts like two days before clouding, but then again it was only 1/3 filled then. We hesitate to wc more than 2-3 times a week to not overly stress the crab out. We use brackish water, about 60-40 salt to fresh water. The filter is washed each time we water change.

There’s probably more but I can’t recall absolutely every detail just sitting down deciding to post so feel free to ask questions whether to get ideas because your little brother made a not so great decision or because you want to correct me. See you around everyone! Promise to update at least once a week (summer is here so I got plenty of time to be bored and come back here haha).


Sent from my iPhone using Tapatalk

[myllkti]

This post is basically “what little we do know”

I also should’ve mentioned we anticipate being able to get it in a 30 gal by the end of July if all goes well. We also maybe able to get some substrate (playsand has been recommended). We hope for 2-3 inches of playsand at least as we know blue crabs love to burrow. We also know that it tends to… eat everything. We can’t help you with much but we have done enough research to tell you don’t try putting plants in there. And by the time to crab is 6.5 in not even an air stone is certified safe. We’re worried about how to attach the filter in a different way where it’s less reachable. My brother also defends our feeding schedule with some surprising solid reasoning- they’re scavengers so they may just get some small amounts throughout the day. Blue crabs need a lot of space. 40-55 should be survivable for a while but by the time it reaches its full 9 in it should be in no less than a 75 gal (again that’s so minimalistic that people have struggled with 90-120 gal tanks).

After the crab molt, wait a minimum of 12 hours to feed. It’s claws are too soft to grab the food so it’s pointless and produces ammonia when crabs are already wasteful animals. There’s also the risk of it hurting itself trying to get the food. You can even wait 48 hours before feeding to be safe. We gave it 24 and the crab was able to eat, but we didn’t give our regular meals until the next day, that was a small snack/test to help mitigate any hunger and test if the hardening period had passed enough to eat. Before it hardens fully it is called a paper crab. It is still partially paper. Paper crabs can eat after a day or two, but for several days choose “flight” over “fight” to avoid injuries. After it has hardened, it is a "tin can"for its newly vibrant color and fresh white bottom. Over time, it will "rust" as brown algae grows and it gains other marks on the old shell, turning into a "rusty crab".


Sent from my iPhone using Tapatalk

[myllkti]

Hello again! Was not planning on posting today, but my brother really wanted to share more info! He was so excited by the idea that this would help someone, he was all like "Will people actually be able to use this?" lol

Anyways

- blue crabs will grow faster in warmer water. As far as we know there is no minimum water temp for them beyond just not making it colder than it naturally would be in the room but if you for some reason that I couldn't guess at want that crab growing, higher temps will help

- if fed well, a crab that's 2 in will only take about 4 months to reach 4 in in captivity. Crabs start at 2 mm and molt every 3-5 days, growing by 33% at a time. More molt info at https://www.beach-net.com/whats-here/cr ... g-game.php

- as scavengers, there's not much blue crabs won't eat- fish that just dies, mussels, clams, oysters, smaller crustaceans, paper crabs, etc. In fact, this makes them an incredibly important part of the ecosystem.

- mature males are aka jimmies, immature females are aka sallies, and mature females are aka sooks

- to sex a blue crab, look under the carapace (body). If it's apron (the shape in the middle) is triangular, it's a sally (immature female). If it's large and round with a point at the top, it is a sook (mature female). If the width is low and the point in the middle is long, it's a jimmy. If both claws are red, then it's a female crab. If one claw is red but the other is not it is a male. Jimmies may also have both orange claws.

He told me more but I forgot. I'll be back either later today or this weekend or some other time entirely. Who knows at this rate

[myllkti]

Also ideas for what else to add would be much appreciated <3


Sent from my iPhone using Tapatalk

[myllkti]

Some food related updates

- noted before too but since it’s coming back up sometimes the crab will hold food for a while without eating, usually seems to eat eventually, and it rarely happens that I’ve personally noticed anyways. I’ll check w my brother later and edit in

- just discovered it’s nocturnal so scrapping our current feeding system. We will be feeding a couple pieces at night now, maybe in the morning if we happen to wake up early


Sent from my iPhone using Tapatalk

[myllkti]

Hello guys I do have a journal update coming up (maybe tmr?)but for now I found a nice documentary so here's a informational update.

I guess we can "title" this one Blue Crabs Breeding in Nature. I also edited in misc info where relevant in previous posts and I will link the documentary at the bottom of this

As a sally decides she is ready to mate, she will seek out a jimmy. Upon finding one she would like to mate with, she will sound out pheromones to communicate that she is here to mate, not fight. She will slowly waft these in his direction. Once the jimmy gets the message, he will swim over on top of the sally and lock her under him. They are now a "doubler". Together, the doubler swims into a patch of grass to seeks safety. Then, the sally will begin her "terminal molt," the last molt of her life, and come out a sook.

Now, before the sook's shell hardens, the males' two gonopods will come out form behind apron, and insert one sperm packet each into the sook's corresponding gonopores behind her apron. The paper crab stays under the jimmy for a day, sometimes a few. He protects her as she hardens and her eggs fertilize. Then he leaves and she swims for up to two weeks to the mouth of the Chesapeake bay. Then, she lets her zoea go.

[myllkti]

This is a bit late (insanely busy weekend sorry guys) but what I wanted to say basically is

The crab has been very active in the day time although it's nocturnal, even after we changed up feeding. My brother hoped maybe it was just more active at night but maybe didn't ever really need sleep but we did more research and it is in fact supposed to sleep in the day time. We will continue feeding this way as it's not exactly going to hurt but need ideas on how to encourage daytime sleeping. Hoping to get the crab into a 30 gallon tank so the more space of calm between filter and bubbler hopefully helps, as well as maybe covering an additional side of the tank if still needed (2 sides currently covered as it's against the wall/corner)

I also had an estimate of initial tank set up costs by someone a bit more knoweldagable and it was $200 not including tank (as I said we already have some tanks). According to them, this included a calcium based substrate, a filter, a ver small protein skimmer, testkits, bacteria, and lighting. The minimum size for the crab is either 75, 90, 100, or 120 gallons (not really a common pet, not much discussion and thus consensus) so that would be a hefty price too. Plus additional costs throughout the care journey as they said saltwater anks require more maintenance than freshwater. Yikes

Hopefully this info helps someone a bit

[DragonsFly]

Interesting! How did you (your brother) end up with this crab?

Also, with respect to the breeding information you shared, does this mean that a female blue crab will only breed once? Or is she able to breed more than once after she is a "sook", even though she will not molt again?

[myllkti]

Hello! We were at a housewarming party and the house was near the beach, so someone caught a few crabs and my dad let my little brother take one home *sigh*. And this the journey to learn how to take care of a blue crab begins. At least he learned his lesson about kidnapping wild animals I guess

And yes! It does mean they can only breed once, with up to 2 million eggs! That’s why it’s super important to not kidnap female crabs. Well don’t kidnap any crabs of course, but the females are the only hope of saving the dwindling population. Luckily, ours turned out to be male, but there were likely females in the box


Sent from my iPhone using Tapatalk

[DragonsFly]

Wow, I can see how that makes them very vulnerable as a population!

Now that your brother has had his "teachable moment," do you live near enough that this blue crab could be re-released into the wild to resume the life he was meant to live?

[myllkti]

Unfortunately it’s too far for that. We’re trying to upgrade the tank soon, and get some bacteria, maybe a protein skimmer, etc etc. or cull it. Whichever my dad agrees to


Sent from my iPhone using Tapatalk

[myllkti]

There has been quite a lot but first some pics I snapped of the tin can crab (more on why it it was even upside down (and still sometimes flips) later)



Not the best quality but maybe this helps someone a bit somehow


Sent from my iPhone using Tapatalk

[myllkti]

Hey I'm back! The context surrounding the above pictures is now here!

The crab one day begin to swim at the tank walls and go up, up, up until it would flip upside down. We had to use a chopstick to help it back because Google said they can't breathe like that, and it continued to flip and the cycle continued. So we consulted some discord people and it was bc the crab was getting more desperate for good conditions so it was trying rly hard to escape Did an impromptu water change and fed it some crushed up eggshell (calcium was suuuper important, they said) and it stopped flipping as much!! There's probably more but hope that helps for now. See ya next time folks! (btw it passed but there's a lot before then I didn't update so that's what I mean)

[DragonsFly]

So sad. One more story with the moral: leave living things in their natural habitat.

[myllkti]

Mhmm. On the bright side by using the crab I convinced him to let go of a frog he rescued fairly easily