hi,
Setting up my tank for cold water fish. Can I use large sea shell in the tank for decoration? (not shell chips) would it be harmful for cold water fish in the long run?

Hi and welcome grouchzzz!

Does the shell has any sharp edge? Unless it's very shard and can hurt you then you can use large sea shell in tank for decoration. Some fish may even use it as a hiding place. Just make sure it's clean and disease free!
_ To do this, soak it in boil water for 24h hour. Do not boil it, soak it in hot water. I also rub it in tap water so any hard particle will fall off.

Also is this the first tank you've set up? If you have you heard of the nitrogen cycle?
http://www.fishkeeping.co.uk/articles ... hless-cycling-article.htm

If the shell has dried out then there will be no pathogens/disease so it should be fine. A good rinse under tap water will sort it. As nathan has mentioned though, sharp edges and goldfish for example, don't mix too well.

Shells will release calcium slowly but given where you live - highly likely that you have soft acidic water - you may need to buffer the hardness anyway with crushed shell in the filter - for coldies.

Coldwater/temperate fish are varied and diverse. What are you considering keeping? What is the tank size?

Your local waterboard website should give a clue as to pH and GH - area where you can type in your post code - which kind of dictates how you go forward

the shell is in the garden for years just as a decoration. i have washed and scrub it throughly. there are some long pointy edge. i will feel it later. if there are sharp, i will remove it. thanks for the advice.

i read the nitogen cycle from here. going through it just now. will test the water.

thanks for the advice

Was given a baby black blue oranda and a biord.
had him for 5 years already. (Lt Shiny sides)

never really like the Biord but thought nothing more about it. had gold fish in a bowl when i was small and always think that gold fish doesn't live long.

Lt shiny sides turn 5 years old and i think it's about time for a bigger home for the old bot. a more comfortable life for his old age. didn't realise he is just in his mid life is he life to mature age.

got a tank from friend -75x30x30 cm.
hence, starting the new tank. just realise even that is not enough for him. can't have any bigger tank than that.
i know it is not ideal but it is definitely better than the biorb.

Sorry but I think your fish is stunt... Normally in 5 years, the fish should be bigger than a biorb already.

If you want him to be happy for the rest of his life, rehoming him is the best option. You can keep many small specie in your new tank but definitely not a goldfish

Hence the bigger tank.