How can I tell if it's safe to put new fish in my tank?

[N3PTUN3]

I recently added six cardinal tetras to my aquarium. Unfortunately, within two days three of them had died along with two of my zebra danios that were already in the tank.
I don't know why they died, but my water chemistry was ok, so I guess it must have been some sort of disease brought in with the cardinals.

0.25 ammonia
0.1 nitrite
< 5 nitrate

That was three weeks ago and the water chemistry is still fine. The remaining 3 cardinals and all of my other fish appear to be healthy, but how do I know that the water is safe (from a microbiological point of view) to put more fish in?

I am worried that there might be some sort of bacterial/fungal infection in the water that killed those other fish, but somehow did not kill the others.

 

[jlk]

I would not add anymore fish until your ammonia & nitrite are zero and have stayed zero for atleast a week or two straight. Right now, your in the midst of a fish-in cycle. You likely had spikes in ammonia and/or nitrite after adding the other fish and this contributed to their demise.

I just learned about cycling but I already have fish. What now?! - Aquarium Advice

 

[N3PTUN3]

I would not add anymore fish until your ammonia & nitrite are zero and have stayed zero for atleast a week or two straight. Right now, your in the midst of a fish-in cycle. You likely had spikes in ammonia and/or nitrite after adding the other fish and this contributed to their demise.

I just learned about cycling but I already have fish. What now?! - Aquarium Advice

Hi

No, I didn't have any spikes. I check the water at least once a day (pH, Ammonia, Nitrites and Nitrites). Tank has been set up since April 1st. You could be right about being in the midst of a fish-in cycle. My local aquarium retailer suggested i had had a 'stealth cycle'. I made other posts about this.

After more than two months with fish in you would expect it to be cycled, but personally I'm not sure. But there have never been any spikes. Additionally, my pH is 7, meaning that any ammonia present in the tank is likely to be in a less harmful form. I don't think the water chemistry was to blame, I think it was microbiological or possibly stress induced death.

What i want to know is whether it is possible to tell if there are any microbiological problems in the tank.

cheers

 

[jlk]

Well, I am sorry but with ammonia & nitrite present, your tank is not fully cycled. I am not sure what your lfs is referring to as a 'stealth cycle'- do you mean a silent cycle? A silent cycle is cycling with tons of fast growing plants. Is this what you have been attempting?

In respect to microbes or harmful bacteria, they are always present. There is no way to completely erradicate the 'bad' bacteria without destroying your 'good' bacteria. A healthy fish with a strong immune system is capable of handling exposure to bad bacteria just the same as we are. Everything is exposed to bacteria 24/7 because they are everywhere. If your fish had some type of unknown disease (a possibility), I would suggest waiting a few weeks to make sure no one else has any symptoms & that your ammonia/nitrite are zero to limit stress to any new fish.

 

[N3PTUN3]

Well, I am sorry but with ammonia & nitrite present, your tank is not fully cycled. I am not sure what your lfs is referring to as a 'stealth cycle'- do you mean a silent cycle? A silent cycle is cycling with tons of fast growing plants. Is this what you have been attempting?

I feared as much. I didn't know what my lfs was talking about. I'm new to this and I wasn't really attempting to do anything other than own a nice aquarium. Like so many others, I followed the manufacturer's advice provided with the tank and bought 'a few hardy fish' to cycle my tank. I didn't know exactly what that meant until I stumbled across this website although the lfs did explain about testing the water. I have been tetsing since day one.

Interestingly, I only tested for the first time today using the API kit. Prilor to that i was using the nutrafin test kit, and....everything is different.

The API kit is reading

pH 7.8
Ammonia = 0.5
NitrIte = 0
NitrAte = 0

So, if this is accurate, my tank is nowhere near cycled.
So confusing because it has been running for so long with fish in it.

In respect to microbes or harmful bacteria, they are always present. There is no way to completely erradicate the 'bad' bacteria without destroying your 'good' bacteria. A healthy fish with a strong immune system is capable of handling exposure to bad bacteria just the same as we are. Everything is exposed to bacteria 24/7 because they are everywhere. If your fish had some type of unknown disease (a possibility), I would suggest waiting a few weeks to make sure no one else has any symptoms & that your ammonia/nitrite are zero to limit stress to any new fish.

I do understand that there are microorganisms everywhere and of course I know that broad spectrum antibiotics will destroy all the beneficial stuff too (even although I don't seem to have any yet). I just wondered whether there was a time frame within which you would not add fish, in case there was a specific pathogen.

To give a human disease analogy. Imagine 3 of my 6 cardinal tetras had died of swine flu. The others in the tank along with the other 3 cardinal tetras were lucky enough to be naturally immune to the virus, except my 2 zebra danio, who also perished. Now I have a tank full of fish with natural immunity to swine flu but who have been exposed and may be carrying the virus. I can't assume that other fish, even healthy ones, will be immune. so...

This is getting a bit surreal, but bear with me. What I wanted to know was, at what point can I assume that the swine flu virus is gone, or can I never be sure?

Of course, for now, with an uncycled tank, this is a moot point. I will have to wait a while anyway, but at some point, hopefully my tank will be fully cycled, and I will want to add more fish. I am preparing a quarantine tank, but i would hate to move healthy fish from the quarantine tank, only to find that there is some unknown disease lurking in my tank.

Sorry for the long message, I think all this fish keeping is getting to me. I used to be normal, and now I'm a tropical fish geek!!!

 

[jlk]

Lol! Honestly, 'assuming' your fish died of some unknown mystery disease, theres no way to be 100% sure it is gone because we dont know what it was. Thats alot of assumptions & unknowns to account for! Basically, if your present fish remain healthy & disease free over the next couple of weeks, I believe whatever 'disease' it may have been has run its course and you are safe to add new fish. Qt'ing any new fish is a very good idea to prevent them from introducing new disease into your tank. Good luck!

 

[ML42]

ill throw my 2cents in...

okay if you had a 50% percent fish death population, there could be many factors 1. the fish had a disease, 2. Nitrates ammonia....blah...blah..blah.

If I was you if all my parameters have stayed the same for at least 5 days my tank should be well stabilized to sustain a new load (Tip start out slow) add one or two fish at a time, if not your biological load will be thrown of balance, also when you buy a new tank mate, quarantine him if possible if not buy a nitrite reducing aid, this will help a lot since fish can suffer injuries from the tiniest changes in parameters, also adding plants will aid your trates stay really low, if this is not working for you then go to the simple solution do water changes anywhere from 25-45% to reduce and improve H2o quality, I recommend that if you are struggling with parameters it might not just be you, but the tap water you are getting might have high copper, residue, and all kinds of YUK you dont want in your tank, so for the water changes in you do 25-30% you can change that water out for distilled water (Be careful to much distilled will also kill you fish)because the minerals are out of the water so basically your fish is going to supply that, but to make it short and sweet again water changes, a nice acclamation after you buy your fish, and sometimes I add a organic tick mix to the water when the mate is coming in just for prevention, again its organic and it wont kill your plants or hurt the other fish.

Hope that helps I have 2 FW so I have been down that road, if you need help just shoot it to my inbox, glad to help.

 

[N3PTUN3]

Thank you both.
I will have to wait a while until my tank has cycled properly, so by then if my current fish are still alive, I guess i can assume the water is ok.
I'm totally confused as to why my water chemistry isn't changing. I have 12 (albeit small) fish in a 125 litre (33 US gallon) tank. There have been fish in there for two and a half months, and the highest the ammonia ever gets is 0.5.
When i see that I do a 35% water change. Why won't it cycle?

I think the water quality here (Scottish Highlands) is pretty good. Obviously they add chlorine, but there are no heavy metals. Biggest thing is that it is very soft, but not sure whether that matters, or whether it can be changed.
I'm trying to cycle my quarantine tank without fish. Only on day three, so no idea whether this will be more successful.

 

[jlk]

Soft water does make a difference in cycling. Do you know the ph of your tap after it has gassed off? Do you know the KH & GH of your tap? Lack of KH (carbonate buffers) can prevent a tank from properly cycling but without some more information, I dont know if this is a specific problem for you.

You also mentioned that your water does contain chlorine (normal in public water supplies)- do you know how much the average chlorine content is in your water? You can contact your water authority to find this information. In some cases, the amount of chlorine is beyond what a typical water conditioner can handle. So, every water change effectively kills off any good bacteria that has grown (and a cycle starts all over again). Its just another possible factor why you may be having issues with your cycle. We will do our best to help you get things where they need to be!

 

[N3PTUN3]

Soft water does make a difference in cycling. Do you know the ph of your tap after it has gassed off? Do you know the KH & GH of your tap? Lack of KH (carbonate buffers) can prevent a tank from properly cycling but without some more information, I dont know if this is a specific problem for you.

You also mentioned that your water does contain chlorine (normal in public water supplies)- do you know how much the average chlorine content is in your water? You can contact your water authority to find this information. In some cases, the amount of chlorine is beyond what a typical water conditioner can handle. So, every water change effectively kills off any good bacteria that has grown (and a cycle starts all over again). Its just another possible factor why you may be having issues with your cycle. We will do our best to help you get things where they need to be!

Hi again

Well I checked the pH of the tap water after leaving it overnight and it is 6.8. I'm slightly confused about the pH of the water in the tank because if I use the normal pH test it shows the highest level (7.6), but on the high pH scale it reads the lowest level (7.4), but I guess it must be somewhere around 7.5.
As for chlorine, I have contacted the water company, but in the meantime I looked at some of their literature and checked a few more local forums.

Apparently, here in Scotland, lots of people have problems with the water for fishkeeping. They are adding sand??? or coral??? to help with pH, i think. According to the water company leaflets, the permissible limit of chloride is 250 mg Cl/l, but I don't know what the actual level at my tap is. There are no parameters for hardness, but our water is very very soft (we never have limescale and we never need much soap to create a lather here). This water, I believe, makes the most wonderful whisky, but it seems to be bad for fish

How to find out what the levels are at my tap? Another test kit?£?£?£?
And if there are problems are they easy to fix?

 

[jlk]

Thats quite a bit of chlorine! A water conditioner such as Prime will dechlorinate up to 5mg/l of chlorine. Some other conditioners only work up to 2mg/l. This is a definite factor in cycling if your chlorine levels are in the 250mg/l range or anywhere near this amount. If you can find out the average amount of chlorine your municipality uses, we can figure out if you need to increase the amount of dechlorinator or possibly start setting out water with a bubbler a few days in advance to use for water changes (chlorine will dissipate).

Yes, as you are discovering, using crushed coral, argonite, limestone, crushed seashells or a carbonate-based sand (not quartz/silica) will help to increase your carbonate levels (KH). If your carbonate levels are low to nonexistent, it will make cycling difficult because your bb need carbonates in order to process ammonia. Thats an easy fix- you can either add one of these to your substrate or place some in a mesh bag/piece of panythose in your filter. If you have a decent lfs, you can take a sample of your tap to them & have them test your KH & GH to see where they sit without having to buy another test kit. Hope this helps!

 

[N3PTUN3]

Thats quite a bit of chlorine! A water conditioner such as Prime will dechlorinate up to 5mg/l of chlorine. Some other conditioners only work up to 2mg/l. This is a definite factor in cycling if your chlorine levels are in the 250mg/l range or anywhere near this amount. If you can find out the average amount of chlorine your municipality uses, we can figure out if you need to increase the amount of dechlorinator or possibly start setting out water with a bubbler a few days in advance to use for water changes (chlorine will dissipate).

Yes, as you are discovering, using crushed coral, argonite, limestone, crushed seashells or a carbonate-based sand (not quartz/silica) will help to increase your carbonate levels (KH). If your carbonate levels are low to nonexistent, it will make cycling difficult because your bb need carbonates in order to process ammonia. Thats an easy fix- you can either add one of these to your substrate or place some in a mesh bag/piece of panythose in your filter. If you have a decent lfs, you can take a sample of your tap to them & have them test your KH & GH to see where they sit without having to buy another test kit. Hope this helps!

Hi again

No that's the maximum for chloride, not chlorine (whatever that means ). I found another of the Water Company's leaflets that indicates that chlorine and chloramines will be harmful to fish, but states that products for removing these should work.

I asked the girl in pets-at-home (local pet store) for advice today, but i don't think she knew what she was talking about. She said I'm probably not seeing nitrate because the fish are using them up. She says if my fish look healthy then it's probably fine. When I questioned her about the fish being able to 'use up' the Niitrate, she looked at me as though I was being a bit dim and asked if i knew about the Nitrogen Cycle.

She said my pH at 7.4, is too high and offered to sell me a product to bring it to pH7. It cost £10, and I would have bought it if I had trusted her advice, but I'm just not sure. She said they don't add coral sand to their tanks (they are about 4 miles from my home), so I probably don't need it. They don't sell it anyway. She said they put lots of stuff in their water to stabilise it and they don't have readings for Nitrate either. She couldn't test my water sample for KH or GH because they don't use that kit, but tested all the usual parameters, but she got the same results I've been getting. She also tried to sell me a plant, which she said would help.

She was really nice and friendly, but what she is saying contradicts everything I read on this site. I'm now totally confused and don't really know what to do now. I think my tap water must be killing my bacteria, but I don't know why

This aquarium business isn't as easy as I thought it would be.

 

[smomus]

A ph7 isn't really anything to worry about IMO. Keeping the ph stable is important tho. My ph regularly tests between 8.2-8.6, depending on the tank. Unless you are trying to keep some uber sensitive fish, don't worry about the ph unless it fluctuates a lot

 

[N3PTUN3]

A ph7 isn't really anything to worry about IMO. Keeping the ph stable is important tho. My ph regularly tests between 8.2-8.6, depending on the tank. Unless you are trying to keep some uber sensitive fish, don't worry about the ph unless it fluctuates a lot

Hi

It's funny, I wasn't worrying about it until today!!
I have no idea what's going on with my aquarium. I can only assume something is disrupting the bacteria in the water, because it just won't cycle.

Two different lfs have told me not to worry about it. One of them said, it probably did a stealth cycle, and today, the other one told me not to worry about Nitrates etc, just do water changes and get the pH to 7.

I have no idea what to do now

 

[absolutangel04]

Ok, sorry to say, but many pet store employees have no idea what they are talking about. I know conflicting information is frustrating though. The best I say really say about that is that if you google the things we are discussing and look at articles (not just random forum posts or yahoo answers or things like that), you will find that the opinions being offered to you do have real experience and scientific backing behind them. Like I said, I know conflicting info is frustrating.
Remember this, not every car salesman is a car expert, some just need a job. Not every pet store employee is a fish expert, some just need a job.
Forgive me, but could you please tell me what all is in your tank and what size it is? Some of the posts were rather long so I probably missed the part when you said that.
We will help you get it sorted out. You have been given some good advice so far. Cycles can be difficult sometimes. They don't all go "by the book."

 

[N3PTUN3]

Hi, and thanks

My tank is a 125 litre Juwel Rio (I think this is about 33 US gallons). I unfortunately followed the manufacturers instructions and attempted a fish-in cycle, using 8 zebra danios. I had some problems at the beginning with fish getting trapped between the filter and the glass, so I have lost a few. After that the problem was fine and all fish were healthy until I added the cardinal tetras.

As i intimated in my last post, one of my lfs told me the tank had probably cycled, so I started to add more fish over a period of time. I was using the nutrafin test kit at that time, which showed a trace of nitrate. Now, with API, I see nothing.

Current readings are

Ammonia 0.5
Nitrite 0
Nitrate 0
pH about 7.4

The tank currently contains;

2 zebra danio
4 silvertip tetra
3 cardinal tetra
3 bristlenose catfish

all seem healthy.
First fish were added to the tank on 8 April. It has had fish in it ever since, but as you can see from the readings, it doesn't seem to cycle. Opinion seems to be that my tap water could be the problem. Water here in Scotland is extremely soft.

 

[absolutangel04]

For the nitrate test, you need to shake he heck out of it to get it to go. Try it again and see if shaking it more yields any results.
The absence of nitrite indicates you may be cycled. Good to know you got a better kit.
.5 ammonia is no big deal at all. That level is not toxic to the fish, so no worries there.

 

[N3PTUN3]

Yeah, I did the shaking thing, but it doesn't help.
I don't really understand. After all this time, with fish in, i would have thought it should have cycled, but it has never spiked. I was expecting to see a rise in ammonia, followed by a rise in nitrite and then a rise in nitrate. I have honestly (apart from once when I was sick) tested the water every single day (that's why i had to buy a new test kit). But absolutely nothing except a small rise in ammonia. It's just weird.

I'm trying to cycle another (quarantine) tank at the moment. This time I'm doing it without fish, so maybe this will be different, but if my tap water is to blame, I will have the same problems.

 

[absolutangel04]

Is the tank planted?

 

[N3PTUN3]

No, the plants are all synthetic.