and then there were none...

davidb

We have been keeping mainly tertras for quite some months in our BioUbe tank, and regularly changing filters and water as instructed.

Then 3 months ago, over a matter of 4 days one by one of the fish died much to the horror of my kids. So, we waited for a few weeks, thoroughly cleaned the tank, gravel etc. Then restarted the tank and left it without fish for about 4 weeks. Then re introduced some neon tetras which all died within a couple of days.

Unpreturbed, we rechecked pH levels etc and noticed it was slighly alkaline to popped in a few mollies just yesterday. One died over night. The remaining one looks less than happy.

I kept a lot of tropical fish as a kid, and have never had fish just simply die off in a matter of days. I am getting to the point of throwing everyything away and starting from scratch once again.

WHat pointers does anyone have apart from the usual ones of settling down the tank - which I reckon was done over the last 4 or 5 weeks.

1077

Often times overfeeding or too many fish for biological bacteria to break down the waste from those fish leads to lethal ammonia levels which kill fish. Without test results for ammonia, nitrites, and nitrates. water change schedule and amount of food being offered it would be difficult to speculate. Liquid test kit such as API freshwater master kit sold at most fish stores would be a tool that could eliminate or identify water quality issues and would be where I would start. Test strips are not in my view nearly as accurate as the kit mentioned. Fish will adapt to ph values that are stable and I have doubts that your problem is with the PH. Get the test kit and post the results for starters.

davidb

hmmm?

could only get a nitrate test, and having tested twice - the value looks to be around 5mg.

normal feeding is once a day with flakes (not that much). tank is cleaned once a month and filter replaced 25% water change, stress Zyme used as per manufacturers instructions etc.

During the Aberdeen summer we did have an algae build up, but that has now gone - both the summer and the algae

I have never been a fan for the so-called medicines in pet stores, so we do not use them.

1077

Weekly 10 to 20 percent water changes in tanks 10 gal or larger are the normal recommended frequency for water changes. Tanks smaller than 10 gal. would need twice weekly water changes of no more than 50 percent.

Kim

IMO some medications do work very well, and I have personally used a number of them to save fish that otherwise would have died.

When you broke down the tank, did you recycle it? Do you know what a cycle is? If you just let the water sit for that time without adding an ammonia source, then the waiting period did nothing for the tank. You really need a water test kit for ammonia and nitrite as well as the ones for pH and nitrate that you have. Once we have real readings it will be easier to make a diagnosis.

Weekly 20% water changes are what is normally recommended. Also, staggering the filter change and water change is a good idea so that you do not remove too much good bacteria at once which could induce a mini-cycle.

Did the fish show any other symptoms before death? Did you add any new fish beforehand? Do you use a water conditioner? Where does your water come from? If it is city water, they could be using more/different chemicals in it that are harmful to your fish if the water is not conditioned beforehand.

davidb

the water comes from the mains tap. as we live in scotland this is very good soft water.

The tank did lie dormant for a few weeks with the filter and pump running also added were the stress zyme sachets used to create a new tank.. The gravel was only washed through and not necessarily sterilised so there would be the remains of previous bacteria and various deposits.

just watching the remaining fish, flip over and over from its back to its belly over and over again. However since feeding earlier today it has looked much more alert and active, so this behaviour was unusual to see.

it all seems most unusual. as i mentioned i have kept fish before for a lot of years and seen nothing like this.

willow

hi
well unless i'm not reading correctly,your tank is not cycled,
bottle material is often of no use,sorry,looks like the fish have
passed due to the build up of toxins that they have produced.
have you any friends with a tropical set up,if you do,as them to
give them some mature filter media,to put into your tank filter.
what a shame you're not near me.i've got a bucket load of mature
filter waste that you could have had,not that it will help you at the moment.

iamntbatman

It's hard to speculate about what killed off your fish initially. I would think that poor water quality in an established tank would show itself much more gradually, with fish suffering from the high nitrates for quite a while before finally kicking the bucket. If I had to guess, I'd say there was likely some sort of disease that did your fish in.

However, as others have pointed out, leaving a tank empty for a month without an ammonia source will starve the bacteria, even any that were remaining after the complete tank cleaning. I would doubt that you had much at all left in the way of a biological filter after a month with no fish. The second batch of fish could have been diseased when you purchased them but putting them into a tank that has become un-cycled would have been very stressful.

In my experience, you cannot always rely on things like Stress-Zyme to cycle your tank for you. I've always had more luck with patience and an ammonia source to allow the tank to cycle naturally.

davidb

this has all been very helpful and supportive, and i can agree that patience is perhaps the best course of action.

the intention is to slowly re-build the tank over the next few months. and i shall keep you updated with the progress (forever the optimist).

many thanks to all of you who took the time to give me advise / wisdom. Much appreciated

davidb

Hi
thought I would give you an update.
We decided to start all over again, and build the tank up from scratch. Popped in 3 platys and all was well.
Checked ammonia and nitrates, and used water changes to keep them in check. We even had some babies !

The tank was running well for about 5 weeks. Then out of no-where the 3 platys died within 48 hours of each other. All chemical measurements seem OK - ammonia was down, and the nitrate spike had passed

Just to re-iterate we have a Bioube tank, and the only thing we can think of is that the filter mechanism is the problem