Houston We Have A Problem...fish Dying...

[Aquamaniac]

Hi

My tank has been working for almost 4 months now. For the last 3 months i had guppys,platys,and mollys wich i was keeping in my tank untill i could get a new home for them because my wife's tank was overstocked.
But 2 weeks ago i finally gave them away and put in new stock.But now they are dying one after the other.

First the setup:

Tank: 120x50x40 (240 lts aprox.)
heater: Fluval mirrored M 300 watts ( water temperature at a steady 25 degrees celsius)
Filters: Fluval 305 (working since the beggining)
Eheim 2215 (added 3 weeks ago)
Co2 : Pressurized co2 6 hours daily
Lighting : 2x 54 watts 6 hours daily
Substrate: Tesco's cat litter
Fertile soil: mixture akadama from my last assembly mixed with tropica aquacare


Stocking:

6 Zebras danio (they were 10 two weeks ago)
6 Glowlight danios
3 Siamese algae eaters
6 ottocinclus affinis
6 amano shrimps

Ph: 7.0

Adding: Macros 3x week
Micros 3x week
10 ml of easycarbo ( had a algae problem recently)

I ordered the API master kit but so far it has not arrived so i can not get all the other water parameters.

Basically for the past few days i'm having a fish dying every day. Except for the one of today
they all died during the night without any apparent sympthoms that something was wrong during the day.
I just wake up check the tank and one of them is dead.No explanation.
I have done one 50% water change days ago.
Today i came home from work everything was fine.
I went to watch the Denmark-Portugal game and when i get back after, one of the zebra danios was lying on the substrate. He was barely alive and died even before i had the time to try to move him to the quarantine tank.
For you guys to understand the only fish dying are Zebra danios. All the fish look lively and happy even the shrimp.
So after that i did a 70% water change. Now they look fine but i am already worried about tomorrow when wake up or when i come from work in the afternoon.

I don't have the tests at hand but my best guess is i'm having something really wrong with my water.

Possible reasons:
1- Something messed up my bacterial colony and my fluval is cycling again, i do believe that my eheim 2215 is probably still cycling.
2- My bacterial colony was not enough to cope with the extra fish
3- I was having a massive algae problem, and with reduced light hours,algae eaters,water changes,more strict fertilizing regimen and daily doses of easycarbo that tank is mostly algae free. My idea is if easycarbo killed the algae it would have caused a decrease in water quality as ammonia would have been realeased.
3- Some sickness that i am yet to find any simptoms.

My questions:
1- Why only the Zebra danios and not the all lot of them?And i heard the shrimp are very sensitive to water quality problems and they look fine and happy.
2- Is there any disease that only afects danios that i am not aware or is it even normal for them to just drop for no reason?
3- I've done 3 major water changes since saturday it should have helped stabilize the tank.

Its bad that i don't have the tests it could atleast shed some light into how my water is really doing but still i'm not really used to having fish just dropping dead for no reason.

Dunno what more i can do to keep the fish from dying, this afternoon while i was watching the game i was keeping an eye on the tank and to be honest things were fine,then five minutes after i looked and the fish is seconds from dying.
Even if something messed up the bacterial colony in my fluval 305 with the amount of water changes i'm doing it should be helping me to control the situation.

Sorry about the big text i just needed to share my problem,as i am really upset with myself for not knowing why they are dying and for not having ordered the tests earlier.

 

[Fish4]

Hard to say without your water stats. But suspect water quality could be an issue.
Adding macros- micros- algae treatment could be involved?
I had 4 danios as my first fish, loosing one and another injured after them being trapped in a plastic plant.
When i got them i didn't realise they do better in cooler water, around 18-20C, as they're a sub tropical species. I'd love to get more, but as i keep my tank at 24deg not sure it's a good idea now.

 

[Aquamaniac]

I read they can live in temperatures up to 23c. I tried to put the temperature down to that number but even though its raining alot in london these days its not cold so i can't seem to go below 25c.
As for the fertelizers it would be awkward for them to be the reason i think,as for the easycarbo i dunno if it could be the reason.
Can't wait for the tests to arrive.

 

[Aqua Girl]

One of your fish may be cannibalistic my grandmother had a tank full of six tetras and they died off one by one and then when they floated to the top they were chewed up with tails and fins missing so you may a bully fish

 

[Aquamaniac]

Hi

My water tests finally arrived today.
The last big water change i did was 2 days ago and since then no fish have died or show any evidence that they are not ok.

The test kit is a API freshwater test kit and here is my results:

Amonia: 0.25 ppm
Nitrites: 0 ppm
Nitrates: 80 ppm
PH: 7,6

So i what come's to my attention is that there is amonia in my water and that it is probably the reason for my problems. The fact there is no nitrites appears to be irrelevant at the moment since this excess amonia will soon turn in to nitrites and those will become a problem too.
Also nitrates is high.I do know its not as harmfull as the other two but i do wonder how this number is affecting my fish. I do not think i have enough plants to consume the excess nitrates. I have to check my tap water to see how much i am adding with every water change.

What do you guys think?
I do know this ammonia is not good and is what is probably killing my fish.
But nitrates are off also and to be honest i don't quite understand how it might be affecting my water.

 

[The Taffy Apple]

I would dismiss the theory of the high NitrAtes causing the problem (higher than usual 'trAtes are usually a good sign). So i would agree with your first point, the Ammonia.
How did you cycle this tank? Is it possible it has been runnning with fish for 4 months, or did you complete a fishless cycle?

Terry.

 

[Aquamaniac]

I would dismiss the theory of the high NitrAtes causing the problem (higher than usual 'trAtes are usually a good sign). So i would agree with your first point, the Ammonia.
How did you cycle this tank? Is it possible it has been runnning with fish for 4 months, or did you complete a fishless cycle?

Terry.

Yes ammonia gets my vote too. Nitrates could cause algae but right now i don't have problems with that.
The tank had to be a fish in cycle, my wife's 75 litre tank was more than overstocked, she love's livebearers and with them it tends to get that way.I had to put some of her fish in my tank and tried to control things by doing water changes every two days.
The thing is the fish that were added during the cycle are still alive and well back in her tank. They stayed in my tank untill 3 weeks ago and when i finally was able to move it added stocking of my own.

The dying started 2 weeks after and only with the Zebra danios.
I added a second filter almost a month ago,this one should be still cycling but the original filter should have kept the tank running.
I did have a very big problem with staghorn and black brush algae weeks ago,i managed to get rid of it but maybe the dead algae caused a ammonia spike.I removed as much as possible by hand but maybe i did not removed enough.

 

[The Taffy Apple]

if your wife, and you, have other mature tanks then there should be no reason why you should be doing a fish-in cycle.. why not simply add some of her mature media across to the filter in the new tank?

Terry.

 

[Aquamaniac]

We only had the small 75 litre and the filter is internal there's no way i could take the media from there for my fluval 305.i moved house in the end of last year. Took me some time to settle so i managed to move the small tank from one house to the other on the same day as some of its water. But the big tank was deactivated and put in storage for 3 months. So there was no mature media from it i could use 3 months after.
When i said i could not share media is because the small internal hardly has any in it.specially to share with a big canister filter.