As many of us go down the path of natural filtration methods for our aquariums, live rock seems to be the biggest investment made for dentrification. Whilst good quality live rock is unarguably excellent at it's job, it doesn't hurt to have a little extra help, and if it too is natural? Well read on........
Whilst reading a post in the forum I often frequent, it was mentioned about using live tropical oysters to filter the aquarium. The eBay link provided showed the seller asking for £4.50 plus postage for these creatures. A reply was made concerning oysters that are sold in the supermarket. Apparently, although farmed and raised in Scotland, the oysters used for human consumption in the UK are Pacific oysters, with origins in much warmer climes. These oysters are available in Morrisons, Sainsburys and Tescos (I am sure there are others too) for about 50p each!! Below I will detail my acclimatising them to my aquarium.
I don't know about you, but when I buy food from the shop, I expect it to be dead, not so with oysters!! You need to choose an oyster with a closed shell, if it is in any way open, it will be bad and of no use to you. When the oysters are farmed, they are packed in ice for the journey to the shop, where they sit in a refrigerated cabinet, possibly on top of ice. The first job is to remove the oysters from the packaging and place them in a container suitable for holding water. DO NOT add any water at this stage, just merely place them somewhere they can reach room temperature.
It is very weird watching shells. As the oyster warms up, it begins moving around. This can cause the shell the "seesaw" around the container which is a little off putting. Gradually start adding water from the aquarium they will be living in until the shells are covered. This should ideally take about an hour, although you can take longer if you wish, but don't rush it. By the time the shell is covered, you should find that the two halves are opening a little, this shows that the creature is well and truly alive. At this time, you can remove them from the container and place them in your aquarium.
After a few hours, you will find that the shells will "gape" allowing you to see inside the oyster. They are not a very pretty sight, but I am lucky enough to be able to sump mine. They will still be able to filter feed and will also release gametes into the water column providing a plankton supply for the corals and other filter feeding organisms.
I will be keeping an eye on the progress of the oysters and will follow up when there is some progress.