These are the easiest creatures to get hold of as they’re everywhere and they’re so simple to catch. Drag your net into any seaweed attached to rocks and chances are it will come up full of prawns.
I’ve watched it happen and the prawn extends a lot of energy freeing itself from the old ‘shell’ and afterwards it’s kind of just spent and lies there, sometimes on its side. This is when the crabs must pounce and I’ve seen it happen a couple of times, which meant I was able to intervene. Unfortunately I’m not there watching 24/7 and some prawns were ambushed during the molting process.
Interestingly, the smaller prawns I introduced (I haven’t been able to catch any of the really big ones as of yet) really thrived and all have survived in the tank without any issues. This may be because they haven’t yet ‘molted’, I don’t know.
There are no longer any crabs in the tank to hunt them down though so I’m hoping for a lot less prawn fatalities now.
Prawns bring a lot to the tank in terms of clean up, but they’re also very active which means there’s always something to look at. The common prawn should be a staple of any rockpool aquarium in my opinion. I’m hoping to get hold of some of the really big ones at some point, but they’ve been tricky to track down so far as I think they live in the sea rather than in the pools.
One thing I forgot to mention is that they aren’t as harmless as they seem. I was trying to grow some baby flatfish in a breeding net but after a crab attack I decided to put the prawns in there for their own safety until I could return the crabs back where they came from. The next morning all six flatfish were dead, with their tails looking like they’d been shredded.
Several of the prawns ended up with a belly full of eggs which they carry around outside their body (see image below). As of yet, none have actually done anything with those eggs, they’ve been carrying them for weeks.
