Cold water marine aquaria

[Marineboy]

To address the question of "why?" even before it comes up - a cold water marine aquaria is a wonderful way to study out native creatures. They can be successfully kept and later returned to their original habitat with a few basic requirements met in their capture, transportation, housing and subsequent release.
Now my question - do you keep, or concidered starting up a cold water marine aquaria?

[annes]

For me yes, coz for what I know cold-water environment is important on holding (not just study out native creatures) variety of Antarctic fishes and invertebrates. The underlying principle behind this is to provide a controlled environment in system that is simple to maintain. One of the most environmental conditions is the supplying of a continuous low air temperature and sea water temperature. To do the transfer of specimens between holding and research without substantial difference between air and water temperatures. In this way specimens are freed from the dangers of temperature stress.

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Water Resources: PX Pressure Exchanger

[zan]

I thought about it, but it's a lot of work to keep one. Since I dive anyway, I'll just stick to what I can find there

[Marineboy]

Temperature stress is closely linked to oxygen levels - generally as water temperature goes up, it more readily gives up its oxygen, and you don't need a lot of biological load to strip the oxygen from a small volume of water.
For transportation I use one of the solid state cooling picnic boxes. The one I have has got the cooling element in the lid and it copes well even in summer. The water itself is contained in a strong, quality plastic bag within the box to stop it splashing the cooling element while in transit. To keep the oxygen levels up I use a simple battery powered air pump with a small diffuser on the end of a short length of aquarium airline. These little pumps seem reliable and will quite happily run for hours on a couple of D-size batteries.
The top of the bag is tied off tight enough to stop water splashing out, but loose enough not to constrict the airline going in and allows air pumped in to escape.
I also include a thermometer with submersible sensor, so that without opening the box I can monitor the temperature.


Water kept too long at too high a temperature will be stripped of oxygen extremely quickly which is why children with buckets of "goodies" doing rockpooling end up with lethargic or dead catches. Surprisingly, the most susceptible animal I have encountered is a common rockpool inhabitant. The common hermit crab shows very early signs of oxygen depletion stress, and although a fascinating subject in its own right, is a great monitor on oxygen levels. First sign of stress and they leave their shells. Once oygen levels are back up they quickly rehouse themselves.
Without any cooling, or air supply, the life support of a small volume of water, especially in summer can quickly deteriorate.

Using the cold box I have successfully transported from and released back into the sea, dogfish, pollack, gurnard, mullet, lobster, cuttlefish, and numerous other smaller species.
Some people may object to keeping things in captivity, but it allows an intimate study of some of the native creatures of our coast. For example, take the common lobster - they have two very different powerful claws, one for crushing and one for cutting. At least thats what books would have you believe. Yes, both are used for defence, and one is very definately for crushing. But in the four years I had a lobster in a big tank, never once did I see anything even suggesting a cutting action. It has a very different use. Any guesses what?
Fascinating to watch them moult too. And they are more intelligent than we give them credit for. I witnessed things that I can only put down to forward thinking. And of course intelligence goes up a gear with the cuttlefish. Even just out of the egg a young cuttlefish will instictively know which end of a tiny crab it can attack. These I felt were too intelligent to be kept for too long, and with such fast growth and short life span I had to release them. I found the cuttlefish eggs washed up, and hatched them in a nursery tank. Hard work keeping them fed, but rewarding to let them go. Absolutely fascinating creatures.
The lobster was one I rescued from a Cornish fisherman. It was destined for a pot of boiling water, but after several moults and ending up being a little too big, I released it during a dive off Brixham.
This, I see is the beauty of a well set up cold water marine tank. You can take creatures back to where you collected them, and study something new.

[Jim Greenfield]

I kept one for several years to help get my kids interested in marine life. It worked very well for that purpose and we all found it a fascinating hobby. Both of them now dive and take a keen interest in the sea. However, it needs a lot of effort as mentioned above. I wouldn't attempt it now that we no longer live near the coast. Keeping it cool was the biggest challenge and a secondhand beer cooler is ideal I understand from others who have gone in for this in a bigger way than me. The other challenge is keeping it stocked with compatible creatures - put the wrong things in and you rapidly end up with one very fat and contented blenny which is quite distressing.

[Marineboy]

Since the majority of rockpool inhabitants are regularly subjected to swings in extremes of temperature, salinity, pH and oxygen level, they prove to be particularly hardy, but as with all life, they are still very fragile. And remember, the moment you lift them from their natural habitat you are responsible for their wellbeing. These rockpool inhabitants tend to be hardy in a tank at room temperature, but anything from below low water mark generally needs cooling.
Its easy to warm water up, but its more envolved to cool it down. I've tried a small chest freezer, and then got hold of a beer cooler, and made a homemade heat exchanger based on basic physics - it worked well until the lobster took a disliking to it!
As to the water itself, it can be a bit of a chemistry set - There's the ammonia to nitrite to nitrate cycle, pH, salinity, calcium, etc, and if you want you can add all the other trace elements that are used up in supporting life in an enclosed system. Regular water changes are even more important in marine than it is in a freshwater tank and the sea salt is not cheap.
Do it right and its a window on a miniature ocean.
As I said, the moment you lift anything from its natural habitat you are responsible for its wellbeing. How many kids have wanted to take a crab or a fish home from a rockpool? It is possible, but only with a lot of forethought. And always aim to take them back.

[Wildbear]

Hi, I have kept native marine species on and off for years. Keeping them in a controlled enviroment. A long time ago Scottish and Newcastle beer chillers were the bit kit to use, but now aquarium chillers are readily available for the job.

[Marineboy]

Thanks Wildbear. I reckon like many, I was put off by the price of these, but am really pleased to say they have come down in price. Had a look and you can get one for a tank up to 300 litres for about £200 now. My 450 litre tank with sump pump, Eheim filter, skimmer and lights would benefit from something a little bigger and am going to look into it.

[happy scallop]

Hi folks,

I'm coming into this chat a bit late, but just found this wonderful forum :-)

On the subject of cold water marine aquaria, has anyone any experience of holding bivalves (shellfish) in an artificial sea water aquarium?

I'm looking into a small shellfish conservation project which involves holding some scallops in a tank and conditioning them to spawn.

Here's where I need some expert advice: as you know, bivalves are filter feeders. The dense algae culture which will be used to feed the scallops, must remain in the water long enough to be consumed by the animals. Does anyone have any experience of filtration in such a system? Bearing in mind I don't want to take out the algae food source with a skimmer or other mechanical filtration, but still need good recirculated water quality.

Open to suggestions?

[tom00_uk]

have kept and had spawn scallops and mussels in cold water set ups