Fiddler Crabs & Equipment

[SunflowerCrab]

I've been doing a ton of research on Fiddler Crabs and I've found some good stuff. One thing that is giving me high anxiety is not having the correct equipment.

What are the most accurate tools to measure water gravity and water hardness? And salinity I guess?
I've gathered a good amount of sources, but I'm always open for more info. There seems to be very little information for caring for fiddler crabs.

I've heard aragonite sand is the best for nourishing the little crabby exoskeletons and keeping pH stable.
I'm planning on planting pennywort and anubia, b/c those grow well in brackish water. I also want to get some algea growing because this is a good food source. I'm still researching quality internal filters.
I'm starting with a 10 gallon & 4 fiddlers.
I am aware I have to build a shore line and that I have to cycle the tank.

Water temperature 75 - 85 F
Water Hardness 12 to 30 kh
Specific Gravity 1.005 to 1.08

Thanks!

 

[Rocky998]

I know basically nothing about saltwater tanks but I do at least know that the "gravity" of a tank measures the salt amounts... Because salt effects how much gravity water has, you can measure salt amounts with gravity tests... They also do need a land section (I'm fairly sure you already know this). You will definitely need someone other than me... Again, I have never kept saltwater tanks or crabs but I have done SOME reading. But I'm very sure someone else who has wayyy more experience can help... I only gave the info that I was 100% sure about

 

[SunflowerCrab]

Thanks! I definitely did not that's what measuring water gravity meant. I do know I need to build an artificial shore, that's where they live!

 

[SunflowerCrab]

I know basically nothing about saltwater tanks but I do at least know that the "gravity" of a tank measures the salt amounts... Because salt effects how much gravity water has, you can measure salt amounts with gravity tests... They also do need a land section (I'm fairly sure you already know this). You will definitely need someone other than me... Again, I have never kept saltwater tanks or crabs but I have done SOME reading. But I'm very sure someone else who has wayyy more experience can help... I only gave the info that I was 100% sure about

What tool do you use to measure water gravity in your tank?

 

[Oblio]

What tool do you use to measure water gravity in your tank?

One way is with a Hydrometer, I remember using one years ago when we tried to keep seahorses.

Disclaimer: I know little about salt-water tanks, but a fair amount about physics/science. There may be better ways to measure in the hobby.

Hydrometer - Wikipedia

en.wikipedia.org

 

[Rocky998]

What tool do you use to measure water gravity in your tank?

I dont have a saltwater tank, I do freshwater. Like I said, I barely know a thing about saltwater BUT I only gave information I was 100% sure about... I font know what those meters are called but I have seen them before... They look like a small clock with one hand that goes up depending on how much salt is in the water... (Thats what I thought of when I saw it)

 

[SunflowerCrab]

One way is with a Hydrometer, I remember using one years ago when we tried to keep seahorses.

Disclaimer: I know little about salt-water tanks, but a fair amount about physics/science. There may be better ways to measure in the hobby.

Hydrometer - Wikipedia

en.wikipedia.org

Do you think any brand would work? I looked them up and some looked to simple, almost too simple....

 

[Oblio]

Do you think any brand would work? I looked them up and some looked to simple, almost too simple....

I would think so. Simple is good, it's just a weighted object that displaces water with a scale. Archimedes principle does the rest. Basic physics.

 

[Colin_T]

A bit late with this information but if you haven't found more info it might help.

Specific gravity and salinity are the same thing. In marine tanks you can use a plastic chamber hydrometer or floating glass hydrometer to measure the salt level. However, these are only good for salinity (salt level) in a certain range (around sea water strength). For brackish water, a refractometer is a better choice and much more accurate. You can use a refractometer on sea water too but it is more expensive than a plastic chamber or glass hydrometer.

A 10 gallon tank is probably too small for 4 fiddler crabs, especially if you have males. They are territorial and will fight. You might be ok with 2 crabs, and try to get females or 1 male and 1 female. You can sex them by the size of the claw, the males have 1 big claw and 1 small claw. The females have 2 small claws. You can also sex them by having a look at their undersie and seeing what their tail looks like. Crab's tails are curved under the back of the shell and form part of the shell. Female crabs have a shorter wider tail, whereas males have a longer more pointed tail. If you Google "sexing crabs", there are plenty of pictures showing the underside and their tail.

Beach sand is the best substrate for them.

They eat plants and most freshwater plants die in brackish water. You can try some plants but remove them if they rot and use plastic ones if you want plants.

You might be better off using a shallow plastic container with brackish water in and the crabs can crawl in and out of that. Bury the container in the sand or put some rocks around the edge and in the container so they can get in and out. Replace the water in the container each day with brackish water made up at least 24 hours before you use it. The easiest way to do this would be to make up a 20 litre bucket of backish water and aerate it. Use that to fill up their bath each day and when you run out, make up another bucket of water.

Feed the crabs a variety of food and replace the food each day.

If possible, let the crabs out each day or at least a couple of times a week to run around the house. Try to confine them to a room without carpet and let them get some exercise. You can wash out their tank and sand while they are running around in the room.

 

[Donya]

If possible, let the crabs out each day or at least a couple of times a week to run around the house. Try to confine them to a room without carpet and let them get some exercise. You can wash out their tank and sand while they are running around in the room.

I don't think I'd trust any type of crab to not get into problems in the average room. Maybe a very special room that's designed with that in mind and that hasn't had any cleaning products used that could leave residues, but otherwise I would expect there would be nooks and places to go in that make retrieval difficult. While not a fiddler, I once had a green crab that hopped out of its tank and followed me out of the fish room and into the kitchen, where it eventually found some obnoxious little crevice and didn't want to come out. After quite some time a hotdog worked to lure it out and it was fine, but I always felt that both finding it and being able to get it to come out was more luck than anything else.

 

[SunflowerCrab]

I don't think I'd trust any type of crab to not get into problems in the average room. Maybe a very special room that's designed with that in mind and that hasn't had any cleaning products used that could leave residues, but otherwise I would expect there would be nooks and places to go in that make retrieval difficult. While not a fiddler, I once had a green crab that hopped out of its tank and followed me out of the fish room and into the kitchen, where it eventually found some obnoxious little crevice and didn't want to come out. After quite some time a hotdog worked to lure it out and it was fine, but I always felt that both finding it and being able to get it to come out was more luck than anything else.

I'm not going to respond to the original quote after this response b/c I don't feel like getting into an internet argument. Fiddler crabs (and crabs like hermit crabs) have modified gills, being away from a certain level of humidity can cause permanent damage to a the gills harming the crab in the long run. A crab never really needs to be outside of its habitat. Especially to run around the house.