29/10/2022
FISH IN CYCLES - when things haven’t gone to plan.
Perhaps you are new to fish keeping and have been told you haven’t set your tank up correctly, you have been told you are in a ‘fish in cycle’ and you’re not sure what this means.
You might have ended up here because -
🐠 Your tank is newly set up and your fish are dying and you’re not sure why.
🐠 You have recently changed your filter and you are seeing all sort of strange symptoms with your fish.
🐠 You have just bought a test kit and you are showing ammonia or nitrite and are unsure how to fix it.
🐠 Your water may be cloudy, your fish swimming oddly, hanging at the top of the tank or swimming very slowly at the bottom, or
🐠 You have just brought a fish and a tank at the same time.
Many, many people fall into the trap of setting up a fish tank, leaving it to run for a few days (or weeks) and then encountering problems very early on.
You’ve listened to the fish shop, you have scoured the internet and you are still not quite sure what’s happening in your tank, or you’re not sure why you are being told your fish are in danger.
The most likely problem is that you are in ‘a fish in cycle’ and your filter does not have the beneficial bacteria it needs to neutralise the waste your fish are producing.
The ‘Nitrogen cycle’ is the scientific process of converting your toxic fish waste from harmful Ammonia, to harmful Nitrite and then into less harmful Nitrate, and it’s this process that needs to happen within your filter.
You need to keep your fish safe from the rising levels of ammonia and nitrite in the tank. Fish in cycling is a process that takes around 6-8 weeks and involves large water changes almost every day.
The most important thing here is to buy yourself a liquid test kit. NT Labs or API master test are always recommended. You should avoid strip tests as they are inaccurate and don’t test for ammonia. Home test kits are not complicated, you don’t need a science degree and it will be the best investment you make as a fish keeper.
Ammonia and nitrite are both highly toxic for fish. You need to keep both of these at zero at all times. If you have a reading above zero for either ammonia or nitrite you must do a water change. How much water you change depends on your readings and you can use maths to help you.
If you have a reading of 1ppm and only do a 50% water change you are still leaving a reading of 0.5 ammonia, which is still toxic. If you did a 80% water change you are left with 0.2 - still toxic. If you do an 80% followed by another 80% your ammonia will be untraceable. If you had a reading of 4ppm and did 2x 80% you may still have a reading above zero, so you need to do as many consecutive water changes as you can to get that reading back to zero, and repeat daily.
Think of it like trying to dilute squash from a glass of drink. If you had a weak glass of squash (a small amount of ammonia) and your pour 80% away and refill with water the squash will be very minimal. If you have a strong glass of squash (a lot of ammonia) and pour 80% away the squash will still be there. You get the idea.
It is a case of daily testing and water changing, bearing in mind that your fish are always producing ammonia, so no sooner have you diluted it, it’s back again. So you really need to stay on top of it. It can take around 8 weeks or more to cycle your tank with fish in and you have to be prepared that you might lose some along the way, and for those that survive they will be more susceptible to illness and disease and live shortened lives as a result. If you have the option to return your fish to the shop, cycle without fish (info in the other pinned post) and then start up again this is by far the best option.
Seachem Prime.
Prime is a dechlorinator, sometimes called a water conditioner. It’s the best value for
money dechlorinator out there as you need to use such a small amount. It claims to have the added benefit of detoxifying ammonia and nitrite and therefore might help you in your fish in cycle. Bear in mind though that Prime is not a ‘treatment’, it’s a bit of a misconception people seem to believe you dose the tank with it and your fish are then safe. You don’t dose the tank, you add it to the new water you are putting into the tank.
The claims of detoxifying ammonia and nitrite are not actually scientifically proven. It says it does it but there is no proof that it does. Nevertheless it is a cost effective dechlorinator and is recommended. Just don’t use it instead of water changes, you still need to be doing those large water changes every day.
Many people believe that you have to let the ammonia and nitrite levels rise or the tank won’t cycle, and only suggest very small water changes. This is not the case. This comes from a time 30-40 years ago when people bought sacrificial hardy fish and cycled with them, and then returned them to the fish shop for someone else to ‘use’. Most fish we buy are not hardy enough to survive the high levels of toxicity, and neither should they have to fight for life in this way. This is animal cruelty and thankfully the world of science and fishkeeping has moved on a lot since then.
Beneficial Bacteria will grow inside your filter even at very low levels and it multiplies extremely quickly. If you let the ammonia and nitrite levels rise too much your fish will die.
Beware of the fish shop that tries to convince you to fish in cycle. They are making money from your losses and making money from convincing you to then buy expensive water treatments to counteract the problem. Beware also of affiliate sites on the internet that are essentially doing the same thing. I am not profiting from you in any way by giving this advice.
It’s probably not your fault that you find yourself here, however, fish in cycling is not humane, it’s unsafe and should only be used in an emergency when you have no other alternative.
