Since this thread has kinda doubled as a Thai Red Claw Crab resource,
I'd like to answer some questions in public I got PM'ed for your benefit.
1. Do I need to cycle the tank for them?
maybe - crabs get hyper sensitive right before and after they molt, and when you buy crabs you never know when that period is, so I would cycle at least 2 weeks before risking it.
2. Are you adding salt to your tank?
yes - but only 1 teaspoon every 5 gallons.
despite what many post, I have found that half of all fine leaf plants may melt at 1 teaspoon every 2 gallons.
3. Are you conducting water changes and adding salt afterward?
yes - but the fewer animals in your tank, and better filter media system you use, the less often you need to water change after the first Month of new tank cycling. keep track of the water you change including the water lost during canister filter service, so you keep the salt replacement ratio consistant, but don't panic if you make a minor salt over or under as most of your fish and plants are forgiving of such things. remember to never add salt to the water you top off simply to replace evaporation. since crabs appreciate the iodine to ease molting, you can use table salt, but it's preferred by most, especially for your plants sake, to use marine salt which includes useful trace ferts, and then dose the iodine separately.
4. Do they eat your plants!?
generally no - but I have found that plant location and type is key. don't plant anything within an inch of the glass or an inch around the base of rocks and wood. crabs like feeling something behind them as they move, so if plant stems are in their way along the very surfaces they keep their backs to, they may cut down those plant obstacle's they find along their preferred sidewalks.
crabs will eat plant dead plant debris, but they occasionally mistake soft hollow stems and feather leaf plants as debris, so avoid soft hollow stem plants such as Anachris, and feathery leaf plants such as Cabomba and Myriophyllum. these crabs are not diggers, so don't worry about your foreground carpet plants, as long as they are out of their one inch crab sidewalks
a new tip for anyone combining crabs with my moss ropes;
try to position the rope top and/or water flow where it catches some of your plant debris left floating at the water surface. the crabs love to munch on such debris while they are above the water line taking a breather.
since I'm posting here, I may as well update you on my latest moss rope projects;
- second Month of filling in but moss still not weeping. I will update when it does.
used single rope with fishing line tie down.
- just started a new rope, will update in 2-3 Months.
used three braided ropes with plants stuffed between the braid seams.
japan marimo ball cladophora
- just started two new ropes, will update in 2-3 Months.
rope 1 - sliced the ball surface into long strips, then lashed them along a single rope with fishing line.
rope 2 - soaking a rope coiled around the bottom of a small glass container full of clado spore from the balls center. later to be transfered to a regular planted tank once clado growth on the nylon is observed. if nylon is found to inhibit growth, I may try a tan color natural fiber manila or sisal rope.
a dozen people have PM'ed me regarding doing their own moss ropes.
please don't be bashful, and post clear visible progress photos here.
be patient, it takes a good 3 Months for your ropes to look presentable.
FYI: here is the fine clear fishing line I prefer using;
this same seller has fine clear line in different weights.
for lashing, 1lb is fine. for hanging & lashing, 4lb is best.
for hanging rock string ornaments, you must use 10lb line.
careful to order the Trilene Clear, not the Blue by accident.