Just Starting out - Fiddler Crab tank (Brackish)

[ChadSmith]

So, I have never had an aquarium before and know next to nothing about them.

I love aquatic life and think crabs are pretty funny, so I want to start out with pet fiddler crabs.



Here is what I think I need:
1. Tank (10-40g) with hood (covered well to prevent escape)

2. Filter - I've been told hang on the back mechanical, bio-wheel, or canister filters. Which one is the best?

3. Heater??

4. Thermometer - monitor correct temperature

5. Hydrometer - monitor correct specific gravity (monitor salinity?)

6. Substrate - play sand? gravel? not sure which is best.

7. Marine Salt - Instant Ocean?

8. Water conditioner - need to remove chlorine and chloramine from your tap water before placing it in the tank. What about using natural spring water or something??

9. Random - Aquarium branches, rocks, etc. I saw someone using PVC pipes as little caves. Pretty cool.


My main questions are:

Do I need to change the water out or will changing/cleaning the filter be sufficient?
What is the ideal specific gravity for a dedicated fiddler crab tank? 1.025?
I don't want a bunch of crabs, so would one male and one female be OK?


Thanks for your patience with an aquatic noob.

 

[SalmonAfrica]

Hey, maybe I can help you:

1) 10 gal should work for a small group, get a bigger tank if you want to keep larger groups.

2) It's hard to say in this case. Since the water level will be quite low (because you need to provide land for the crabs, the water level should be reduced). A canister will work for this setup, but it seems like a bit too much for crabs though. A hang-on-back filter will work but might take strain from having to draw from the reduced water level.

3) Depends on where your crabs come from, and where you are based. Some fiddlers are subtropical so won't mind not having a heated tank; also, if you're in a relatively warm area, they should be fine without heating.

4) Just in case, but all depending on what I said above.

5) A hydrometer measures specific gravity - which in a sense is the salt content of the water. You'll need one of these.

6) Sandy substrate, IMO, looking better than gravel in a crab setup.

7) Marine salt is best, never standard aquarium or table salt. Just go with whatever marine salt is cheapest.

8) Rather go for the anti-chlorine (AKA water conditioner). Spring water has no minerals in it and can be dangerous to use when keeping aquatic life. Anti-chlorine just makes normal tapwater water safe for your pets.

9) Branches and rocks look most natural - try to replicate a mangrove swamp if you can. The rocks and branches will be the 'exposed' (ie: out of water) part of your crabs' environment. PVC pipe, while not so appealing, is very practival in making good hideouts.

Do I need to change the water out or will changing/cleaning the filter be sufficient?

I recommend changing between 10% and 25% of the water every 2 weeks. Take some of the water out of the tank and dispose of it. Then mix some more brackish water in a seperate container (ensuring that it's the same salinity and temperature as the tank water), and put that in the tank to replace the water that you took out.

Clean the filter once a month or once every two months, depending on the messiness of the crabs.

What is the ideal specific gravity for a dedicated fiddler crab tank? 1.025?

Fiddlers can tolerate a wide range of salinities, from pure freshwater at times (1.000) to marine water (which is between 1.023 and 1.028). In this case, you'll be keeping them long term, and you'll want to keep them in a brackish environment. Therefore aim for anything between 1.005 and 1.015.

I don't want a bunch of crabs, so would one male and one female be OK?

I don't see why not. Although I think males displaying to each other and fighting over females would look interesting.

Cheers
Tim