finding dead fish in my tank

Discussion in 'New Aquarium Advice' started by nickgull, Jun 26, 2017.

  1. nickgull

    nickgull PetForums Newbie

    Jun 26, 2017
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    Hi I currently have some small common carp in a large 50lrt tank and I keep losing them I change water every week and feed them twice a day . I also have a very large pump and filtter system in the tank as well as a heater but still keep finding them dead any help or suggestions would be great and much appreciated
  2. NaomiM

    NaomiM PetForums VIP

    Sep 22, 2012
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    Where to start?

    1) Carp should be in a pond, not a tank.
    2) 50L is not a large tank - it's unsuitable for any fish larger than guppies.
    3) Carp are coldwater fish and shouldn't have a heater.
    4) Two feeds a day is too many.
    5) Before putting any fish in a tank, you should to a fishless cycle to get the filter set up ready to process fish waste.

    But the most relevant point here is #1 - your tank is totally unsuitable for the fish you have in it. Get them rehomed to a pond ASAP.
    magpie, Calvine and kittih like this.
  3. kittih

    kittih PetForums VIP

    Jan 19, 2014
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    This is almost certainly a water quality issue. The carp produce a lot if waste, especially on two feeds a day. That waste and any uneaten food produces ammonia. Ammonia is extremely toxic to fish even at very very low levels. Amongst other things it damages the gills so the fish struggle to breathe and then die one by one.

    To keep any fish, there has to be a method of removing this ammonia. Traditionally a filter is used. Bacteria which break down ammonia to nitrite (also very toxic) and others that break down nitrite to nitrate will colonise the filters. This colonisation can happen naturally but it can take 6 to 8 weeks for sufficient bacteria to grow, assuming the filter is large enough. During this time the fish are exposed to ammonia, get sick and will die. Even if they are then put in the correct conditions afterwards the damage will mean they too are likely to die.

    The best approach is to do a fishless cycle which grows enough bacteria before the fish are even added. Google fishless cycle. The filter then can support the fish with no deaths / harm to the fish.

    As @NaomiM says the tank is way to small and carp are too big and messy to live in aquarium. They need a pond. Please rehome your fish to a large pond (don't release them into the wild or a public pond) in someone's garden.

    If you want to keep fish I recommend starting with small tropicals but do a fishless cycle first.
    magpie and NaomiM like this.