Fish keep dying

[Essjay]

I do my water changes once a week and I do around 25% each time

That may be the cause of the high nitrate, depending on just how many fish are in there. Nitrate is the end point of the nitrogen cycle in the vast majority of aquariums, and the only way to remove it is by water changes. Most of do at least 50% a week.

Other causes of high nitrate include -
being overstocked (lots of fish make lots of ammonia which is turned into a lot of nitrate)
overfeeding (uneaten food decomposes to make lots of ammonia which is turned into lots of nitrate)
dead fish not being removed (dead fish decompose to make lots of ammonia etc etc)

 

[Oblio]

Perfect will do this thank you

Double the bottle shake times when the kit is new since it has likely been sitting awhile. Also double the time if you have not tested for awhile.

When you add more fish, that is the time to be checking water parameters more frequently. You are looking for ammonia or nitrite spikes as the BB (Beneficial Bacteria) adjust to the increased bio-load. If you get a spike, follow up with daily water changes until the BB adjust.

 

[Michaela30]

That may be the cause of the high nitrate, depending on just how many fish are in there. Nitrate is the end point of the nitrogen cycle in the vast majority of aquariums, and the only way to remove it is by water changes. Most of do at least 50% a week.

Other causes of high nitrate include -
being overstocked (lots of fish make lots of ammonia which is turned into a lot of nitrate)
overfeeding (uneaten food decomposes to make lots of ammonia which is turned into lots of nitrate)
dead fish not being removed (dead fish decompose to make lots of ammonia etc etc)

OK perfect thank you I'm due a water change today so will do a 50% change today which probably is the cause as I get dead fish out as soon as I see them and I feed them a small pinch twice a day so no over feeding either how often would recommend cleaning the external filter? I do that monthly as that's what it says online

 

[Oblio]

OK perfect thank you I'm due a water change today so will do a 50% change today which probably is the cause as I get dead fish out as soon as I see them and I feed them a small pinch twice a day so no over feeding either how often would recommend cleaning the external filter? I do that monthly as that's what it says online

I would add a pre-filter to the intake to get the big bits and only clean the internal filter when it starts to get clogged with gunk. Make sure you clean with tank water that you siphon off during water change.

Added: By internal, I mean the filter internal to your external filter - lol

 

[Michaela30]

I would add a pre-filter to the intake to get the big bits and only clean the internal filter when it starts to get clogged with gunk. Make sure you clean with tank water that you siphon off during water change.

Added: By internal, I mean the filter internal to your external filter - lol

So by adding a pre filter would I just need to clean this when I do water changes and the main filter when it really needs it? The instructions state to fill with fresh water when I clean the filter is this correct? I've only ever had internal up until now lol so I'm a little unsure with this

 

[Slaphppy7]

Good advice above...and be certain to use a good quality water conditioner when doing WC's, either Seachem Prime or API Tap Water Conditioner

 

[Uberhoust]

I do my water changes once a week and I do around 25% each time

The literature I have read suggests that fish adapt to higher nitrate values so unless your high values are a recent occurrence it might be better to reduce that value over time. If you do a 50% water change your nitrates should reduce by 50 %. If they climb back up to the high value you currently have in a week you have too much stock or are feeding the fish too much.

 

[Michaela30]

The literature I have read suggests that fish adapt to higher nitrate values so unless your high values are a recent occurrence it might be better to reduce that value over time. If you do a 50% water change your nitrates should reduce by 50 %. If they climb back up to the high value you currently have in a week you have too much stock or are feeding the fish too much.

OK thank you

 

[Michaela30]

Good advice above...and be certain to use a good quality water conditioner when doing WC's, either Seachem Prime or API Tap Water Conditioner

Thank you

 

[Byron]

Since nitrates are that high, should she do several smaller changes (25% (3-4)x ) every 6 hours to reduce the chance of osmotic shock?

The literature I have read suggests that fish adapt to higher nitrate values so unless your high values are a recent occurrence it might be better to reduce that value over time.

I discussed this exact issue--reducing nitrate slowly or rapidly--with Neale Monks after it was raised in a thread last year. Dr. Monks agreed with me that immediately getting high nitrates down to zero or as close to zero as possible was not harmful. Fish do not adapt to high nitrate [ @Uberhoust if there are scientific papers somewhere on this, please let me know, I'd like to review them].

Nitrate is toxic to fish; it depends upon the species, the nitrate level, and the exposure time, whether fish die outright or slowly weaken. But the point Neale made is that we are now realizing that nitrate does weaken fish internally, and this usually makes them more susceptible to other issues, so in a sense it is not the nitrate itself that may eventually kill them but something resulting from the weakening impact of nitrate on the fish's physiology and metabolism. For example, Neale specifically mentioned that hole in the head in cichlids is now known to be a direct result of high nitrates over time, as one cause.

So, from the standpoint of nitrates occurring in the aquarium (and not being introduced in the source/tap water), an immediate water change of 70-80% of the tank volume to get nitrate down as close to zero as possible is beneficial to fish. Provided obviously that the parameters, being GH, pH and temperature, between tank water and source water are reasonably the same. Reducing nitrate is not going to shock fish in any way. Think of it like opening the garage door when a car is idling in the garage--you want the toxic gas out as soon as possible.

 

[Byron]

OK perfect thank you I'm due a water change today so will do a 50% change today which probably is the cause as I get dead fish out as soon as I see them and I feed them a small pinch twice a day so no over feeding either how often would recommend cleaning the external filter? I do that monthly as that's what it says online

I have a slightly different approach than other members here. The first job of the filter is to remove particulate matter from the water--this is the "clear" water aspect of filtration, what we call mechanical filtration.

The second job, termed biological filtration because it involves the nitrifying bacteria (or archaea) that deal with ammonia, then nitrite, producing or resulting in nitrate, is important but secondary because this biological filtration will occur elsewhere in the tank, especially in the substrate of an established aquarium. [And live plants negate this a lot anyway.] The brown gunk you see and rinse out of the filter, or siphon out of the substrate, is organic matter. This is a prime source of nitrate, so you want as little as possible sitting in the filter. The organic matter in the substrate is less of an issue (within reason) as it is also the primary source of nutrients like CO2 and ammonia for aquatic plants if these are present. The brown organic sludge in the filter however is nothing but a source of nitrates. Rinsing it out as needed is beneficial. Most of us do not like cleaning an external canister filter as it is a lot of "work," but you could rinse it every week and it would not be detrimental, quite the opposite. The nitrifying bacteria live on the surfaces, and rinsing even in tap water will not remove them, it takes scrubbing and scraping and that you do not do.

 

[carligraceee]

Hi I'm in need to some advice I have a tropical fish tank I've had four fish die in the space of 2 days I've tested my water and the only thing that's low is the alkalinity I'm also struggling with my nitrate levels nitrite is fine but nitrate won't budge no matter what I do levels I change my water once a week but for some reason I keep getting the odd fish die but seems to have been a fair few in the last 2 weeks, I have neon tetras, platys and a bristlenose catfish and it only seems to be my platys which are dying can anyone offer advice at all please would be greatly appreciated thanks in advance ☺

I have noticed Platys are not the hardiest of fish.

I read your numbers, nitrate is way too high. Do consistent, daily water changes with dechlorinated water. Test for ammonia. If it anything about 0, do a 75% water change once a day until it is 0. Add live plants and make sure you are feeding each fish enough of the food their specific species needs as each species needs different vitamins and calories. You can get that information online, platys shouldn't starve, however. They are the rats of community aquariums (along with mollies) and will each just about anything in the tank.

 

[outofwater]

The nitrifying bacteria live on the surfaces, and rinsing even in tap water will not remove them, it takes scrubbing and scraping and that you do not do.

Hi @Byron I've read in other threads that tap water will effectively kill the bacteria due to chlorine and chloramine content. Is that incorrect?

 

[Byron]

Hi @Byron I've read in other threads that tap water will effectively kill the bacteria due to chlorine and chloramine content. Is that incorrect?

Very inaccurate and misleading. It depends upon the level of chlorine, and the exposure time, and the temperature, and even pH ... but chlorine and chloramine will not kill all the nitrifying bacteria according to scientific studies performed on municipal tap water with both "disinfectants" present. More than half of the initial bacteria remained following treatment.

When we set up a new tank, we "cycle" it and this takes anywhere from two to eight weeks normally. Many do not "seed" the tank with existing filter bacteria, but just rely on the nitrifying bacteria appearing and multiplying. Where do these bacteria come from, if not the chlorinated tap water? They are not airborne, that is now understood. They are present in the chlorinated tap water in sufficient numbers to colonize the filter media and multiply when they have food (ammonia, or nitrite).

I have for some 30 years rinsed my sponge filters and canister filter media under the tap. Admittedly, I have live plants (including floating) in my tanks so these on their own will easily deal with ammonia from the fish. But you are not going to kill off all the bacteria by rinsing the filter under the tap. Though I would suggest that beginners initially can use a bucket of tank water just as a cautionary measure; once you get the hang of things, the risk is gone.

If anyone wants to see the paper, here is the link (it is available free):

Comparison of the microbiomes of two drinking water distribution systems—with and without residual chloramine disinfection - Microbiome

Background Residual disinfection is often used to suppress biological growth in drinking water distribution systems (DWDSs), but not without undesirable side effects. In this study, water-main biofilms, drinking water, and bacteria under corrosion tubercles were analyzed from a chloraminated...

microbiomejournal.biomedcentral.com

 

[Oblio]

So by adding a pre filter would I just need to clean this when I do water changes and the main filter when it really needs it? The instructions state to fill with fresh water when I clean the filter is this correct? I've only ever had internal up until now lol so I'm a little unsure with this

That is what I do, with a pre-filter most of the junk is collected there rather than inside your main filter. Wrap a plastic bag around your pre-filter before you pull it off for cleaning to keep from dumping all the gunk in your tank.