Fish keep dying after we go away for a few days

Discussion in 'Fish Keeping Chat' started by HeavenlyWarrior, Jul 17, 2017.


  1. HeavenlyWarrior

    HeavenlyWarrior PetForums Newbie

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    Hi,

    I joined up specifically to ask this questions and I'm hoping that someone with experience can help. We have a small fish tank suitable for 6 fish and unfortunately, over the course of a year and a half, they have died. I have noticed that although we leave them the food that Pets At Home recommend to give them while we are away, the slow releasing kind, when we return they have faecal matter hanging from them and over the floor of the tank, and despite a clear up, they pass away from what looks like infection literally within a day of each other, despite leaving the amount recommended by the packet.

    The tank is otherwise filtered correctly, the water regularly changed, and the fish not overfed while I am at home. But when we go away they seem to die and I am genuinely worried about what is causing it as it has happened a few times now.

    Please advise. Thank you.
     
  2. NaomiM

    NaomiM PetForums VIP

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    Hi HeavenlyWarrior,

    Firstly, sorry you are having problems. It sounds to me like you have been given bad advice from your pet shop. P@H do have a particularly bad reputation in this regard.

    The first thing you need to understand about fish tanks is that they are essentially mini ecosystems, with a balance that needs to be maintained. The smaller the tank, the more delicate this balance is. Basically, any waste and anything that rots in the tank - primarily fish waste and excess fish food - produces ammonia, which is highly toxic. This ammonia is broken down by good bacteria into nitrite (also toxic), which in turn is broken down by another type of good bacteria into nitrate (much less toxic). The primary function of the tank's filter is to provide a home for these two types of good bacteria. The filter media (sponges and/or ceramic beads, sometimes contained within a cartridge) provides large amounts of surface area for the bacteria to inhabit, while the pump keeps the water flowing through it, giving the bacteria a constant supply of oxygen and allowing them to process all the ammonia and nitrite in the water column.

    When you put in one of these "slow-release" food tablets, you are essentially adding a larger ammonia source than you would normally be putting in, which upsets the balance. The amount of bacteria in the filter is adapted to the usual amount of ammonia that there is to process, so when there is an increase in ammonia, the filter bacteria are unable to cope with it all. This highly toxic ammonia poisons the fish, which die and start to rot, producing even more ammonia. Even if the fish don't die directly from ammonia poisoning, it weakens their immune systems, making them susceptible to all sorts of other infections that may already be present in the water, but which a healthy fish would have immunity to.

    If your tank is too small/overstocked, the whole system is likely to be hovering at tipping-point even under "normal" conditions, plus the fish will be stressed by lack of space, further weakening their immunity. Most of the time, the small tanks sold as being "suitable" for a certain number of fish are actually not suitable for anything like that number - in fact they're often not suitable for any fish at all! Can I ask how many litres your tank holds, and what species of fish you have in it?

    Incidentally, fish are more than capable of surviving quite happily without food for up to two weeks. It would happen in the wild, and they are adapted to "starve periods" every so often - in fact, it can even be good for them! Any time that you are going away for two weeks or less, it's much better to leave them without food than to use "holiday feeders". Another option is to add some live plants such as elodea, as many fish like to graze on these - but again, be sure to remove any leaves that are starting to rot, as rotting vegetable matter also releases ammonia.
     
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  3. HeavenlyWarrior

    HeavenlyWarrior PetForums Newbie

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    Hi,

    Thank you for a most informative response, it was far more than expected.

    I thought as much, with fish dying under the same circumstances after trips, I suspected that the holiday feeder was filling the tank up with toxins that were just being recycled by the filter. The fish tank will be completely cleaned out this evening and cycled again in preparation for new fish I will be buying. My partner and I usually do long weekends away rather than week long holidays so I will take your advice and leave them be while we are away.

    Not sure it affects anything but I have noticed that there is a tear in a part of the filter, not in the beads or the sponge or the metal sack, but the tea bag like sack that sits on top of them. I will be replacing this along with adding more plants in there for the new arrivals.

    Some good news though, we have a survivor. While of my last three two of them dies, this little guy was just too ill to move around much and I mistook him for dead. I've moved him to his own little bowel while I do the tank tonight but I'm very happy to see that he seems more active (though he still lethargic at the bottom of the bowel).
     
  4. NaomiM

    NaomiM PetForums VIP

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    Hi HeavenlyWarrior,

    Just a couple of precautions when you're cleaning the tank out. Be sure not to replace all the filter media at once, or you'll be throwing away all the good bacteria. Also, don't use any untreated tapwater to clean the filter or anything in the tank, as the chlorine will kill the good bacteria. Clean the filter media by swishing it in a bucket of old tank water, and make sure all the new water you add to the tank is treated with dechlorinator first. (You may already know all this, but I though it best to mention it just in case!)

    It would be best to keep your surviving fish in the tank rather than moving him out while you clean, unless you're intending to completely change the substrate. You can clean out the tank with him in it, by scrubbing off any algae and doing a couple of large partial water changes (say 50%) using a syphon to clean the waste from the substrate. In a small bowl (presumably unfiltered?), toxins are likely to build up very quickly and make him sicker :( Plus, keeping him in the tank will maintain the existing colony of filter bacteria, meaning that you don't need to cycle again - just introduce new fish slowly, and test the water regularly for ammonia and nitrite (only adding any new fish when both of these levels are reading 0).

    Seachem Prime is a great product that both acts as a dechlorinator and also detoxifies ammonia, so adding a daily dose of this can also help your fish to have the best chance of recovery.

    You didn't say what size the tank is, or what species of fish?
     
  5. HeavenlyWarrior

    HeavenlyWarrior PetForums Newbie

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    Hi Naomi,

    i'm afraid I don't know the exact size of the fish tank, in terms of feet its about 1.5x1x1. Also unsure of the species of fish as there were two species in there who apparently live well together. I just went with the sales assistant's recommendations of species.

    I've taken each step of your advice with the cleaning of the fish tank and am confident that my better understanding of things will result in long lives for the next fish I get at the end of the month when the tank has finished cycling. Unfortunately my little survivor didn't make it through the night despite cleaning the tank with him in it, I think he was just too ill as he was struggling to swim.

    I'll look into Seachem Prime, I've never heard of it but I have a dechlorinator that I have been using - i'll look for something tailored specifically for dealing with ammonia too.
     
  6. NaomiM

    NaomiM PetForums VIP

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    Sorry your fish didn't make it :(

    Now that you have an empty tank, though, the best way to avoid future problems is to do a fishless cycle using ammonia - testing the water daily and adding ammonia doses until the filter is able to process it in 24 hours. When you talk about cycling your tank, is this what you mean? Apologies if you know all this - it's just that many pet shops give advice about 'cycling' that isn't really cycling at all and has little to no benefit.

    If you do need advice on cycling with ammonia, feel free to ask and we can talk you through it.

    Also, it sounds like your tank is around 40L which is too small for many species of fish, including many of the small species because they are active and need swimming space so as not to get stressed. Be sure to research thoroughly before getting any new fish (don't necessarily trust what the shop staff say - after all, their aim is to make a sale). Again, myself and others on here will be happy to help.