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Marine Aquarium -- Crays


Guest Anonymous

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Guest Anonymous

Hello

I am looking to start a marine aquarium and have found a supplier of farmed crays.

Was wondering what size tank I should be looking to buy.

Also if anyone has any tanks for sale that would do the job that would be great!

Cheers

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For cray's:

Crayfish Holding instructions

Aquatic Enterprises ltd Ó.

Introduction.

Crayfish are oceanic animals. The marine environment they live in is rich in oxygen, low in ammonia, nitrite, CO2 and suspended solids. I use these parameters and they are well within the survival range. Parameters outside of these ranges will stress the guys out and they may not show signs of stress right away.

Water Quality Parameters

Parameter Range

Temperature >9 <19

pH >7.9 and <8.4

Salinity Between 32 and 36 mg/L

Oxygen 80% saturation

Nitrite (NO2) <0.1mg/L

Nitrate (NO3) <23mg/L

Ammonia (NH3) < 0.5 mg/L

Temperature

The temperature these guys live in is close to 9C in winter and a high of 19 in the summer. This animal is extremely robust if you have a chiller. If you do not have a chiller unit keep tank out of direct sunlight and away from heaters and fires. They are not like tropical fish and can be sensitive to temperature spikes. Gradual changes are better. Temperature changes in the ocean are gradual.

Salinity

Ensure you slat water source is not close to any fresh water run off if you are using sea water. Try and collect the salt water from clean source. Fresh water can sit on the top of sea water if it has been raining heavily so deeper is better. Try and avoid sediment. Salts can be purchased from pool shops if you intend making you own. The measurement ppt is the same as mg/L and means parts per thousand. Knowing this can help in your calculations of water salinity levels. The best tool for measuring this is a refractometer (makes the job easy). If mixing your own salt water with town supply you will need to make sure you either use rain water or get rid of the chlorine component. Chlorine can be removed by aerating or using chemical sodium thiosulphate.

pH, Nitrite, ammonia

pH, nitrite and ammonia test kits are available from most pet stores. Ammonia and Nitrite can be a lethal combination if they occur together. If your tank is new your water should be changed regularly in the first couple of weeks.

Oxygen

Oxygen is very important. Equipment for this expensive so as a rule of thumb you need to make sure you have plenty of water movement. When water becomes warm the fish need more Oxygen because there will be less in water.

Dissolved Organic matter

The water should be changed before it becomes brown and foamy this is a sign water quality deterioration. Overfeeding will help cause this.

Feeding

Crayfish farming in new Zealand currently relies on fresh mussels for the diet. Mussels are considered a complete diet for crayfish though they may vary in condition seasonally. Some prawn pellets are used successfully in their culture but should be supplemented with mussels at least once per week. Oily fish are also a good protein source.

Substrate

Crayfish are cryptic and prefer to have hiding places. Clean rocks can be placed in the tank so as the animals have a place to hide. Try and create some water movement around the tank so that there are no dead spots for the water to stagnate.

Tank size

Your tank size is not as important as your water quality monitoring. Literature values suggest that 0.15kg/L can be held. The small animals are about 25g (0.025 kg). Obviously it is easier to maintain water quality parameters in a larger tank. I would suggest a minimum tank set up of 20 litres and an under gravel system and an airlift pump. Have plenty of Air if you have no protein skimmer.

Final note

The above guide is designed to aid the aquarist in caring for their pet. If all the water parameters for this pet are met there is no reason the pet shouldn’t live for thirty years or more. As a general note if in doubt change the water. If you have all the tools for measuring parameters there is less doubt.

Be good to your pets and good luck.

Check out this thread http://www.fnzas.org.nz/fishroom/1-vt6838.html?start=0

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Guest Anonymous

Hey guys,

just bought a 120L tank and will be getting the crays soon,

Instead of a cooler I was gonna freeze bottles of water and change the bottles every day or so as required.

Was wondering what other fish I could include in this type of setup so that the fish dont get eaten and can also stand the cool salty conditions.

Thanks

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Guest Anonymous

I was wondering how robust crays are when it comes to salinity level. Obviously the sea is very salty, but at Kapiti Island the river ejects a large amount of fresh water into that area of the sea, diluting an area where many large crays live

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In general, marine crustaceans are fairly intolerant of salinity change.

Although the river may appear to dump a lot of fresh water into the area, I'd be willing to bet that if you actually did a salinity check where the crays are, the difference would be almost imperceptable.

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  • 2 weeks later...

If you want to see some crays in a tank the marine conversation people have moved the octopuss from wellington airport to the reading cinema arcade in town.

His tank has now been segmented into 3 sections, now housing the octupus and a big fat sea cuccumber, starfish and seahorses, and lastly 5-6 baby crayfish and some fish Im unsure about.

Its definatly spurred me into the idea of splitting my tank in half and having crays and sea horses.

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I liked that octopus tank, but it didnt have anywhere to hide, so its a bit creul in my opinion.. (while it was in the airport anyway) I think it must be a new octopus otherwise he's doing real well. I dont spose you could hazzard a guess as to the volume that tank is?

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  • 2 weeks later...

Yeah last time I saw the octopus at the airport he wasn't look to good at all, looked like he was about to die.

This looks like the same octopus (size wise, I can't really tell octopus apart), if it is he's definalty looking alot better. I think he was rescued and thats how he ended up in the tank ... trying to remember the pamphlet I read ages ago.... so I doubt he was ever in good shape.

I think he had a pot but he was never in it and the pot was tiny, I think he's got even less now, just a few items of 'rubbish' showing marine pollution in the wellington area.

I'll try and get a pic but I rarely go to that part of town and rarely have a camera on me. The sea cucumber is impressive though, it's over 6 inchs long and probably 2 wide.

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