Vampire crabs, two have died

[Sunflowerone]

Hi everyone
I'm new to this site so hopefully I'll get this right. I have a half filled 20 litre tank with a floating island, I bought 6 VC three months ago and I've lost three. I'm not sure why they've died, they can easily get out of the water, climbing up wires and hanging around under the lid and on the island.

I've been feeding them bloodworms, flaked fish food, they share the tank apparently happily with tetras. Any advice would be welcome, thanks

[Autumnsky]

This is a 5G tank, that is not a big enough for these guys.

What kind of filtration do you have?

[Sunflowerone]

Hi, I'm using a 3.5 watt, flow 100 L/h filter. Everything I've read says you don't need much water but mines half full and they can crawl out.

[Autumnsky]

Water and land space is good to have but the tanks filter likely hadn't developed the amount of beneficial bacteria needed to process ammonia, nitrite and nitrate and during the cycling process with feeding the protein rich food could have caused spikes which can and usually are potentially deadly.

Have you read up on what the nitrification cycle is, check the thread below has an article link for learning lots of things about how to keep an aquarium and may help you understand the process. There are links for other articles like when you already have fish (and VC) to take care of.

Also I would look into food for inverts, specifically which will aid in shell development and molting. Pure Cuttlebone is a nice addition, or a special type of mineral block. Hikari has a Crab Cuisine and it is pretty economical, say $5. or less. Walmart has it sometimes and Petco, or online it is around 3.99.