Start Up Tank - 6 Fish Dead Within 4 Days

Hello all,

I'm new to here and the fish scene, so please excuse my lack of knowledge on the subject (still learning!).

I have a 52 litre tank, set at 26 degrees Celsius. Contains a Fluval U2 underwater filter, a few plants (real and fake), gravel, pebbles and a few decorations.

Added 6 Harlequin rasbora to the tank after 5 days after adding the water and switching on the heater & filter. I was advised and read somewhere that it was okay to do so, though after doing more research on the net after the dilemma I since discovered that I perhaps should have waited?

Anyways what's done is done. When the first died I was asked by the pet shop to bring a sample of water, they did a test for Ph, Ammonia and Nitrite. The girl advised that the Ph was perhaps a little too high (I don't think she was too sure to be honest). Unfortunately by the time I managed to get to the pet shop four had already died. Three of the fish are accounted for however one is nowhere to be found. I walked away with four more fish (they replaced them for free) and some solution called Ph Down (contains sulfuric acid). Got home to find another dead

Gradually added the Ph Down which did eventually bring it right down to 6.0. After 24 hours all seemed well and all the fish appeared to be happy enough. Last night the last remaining fish (of the original six) started doing the same as the other previous fish by acting really unsocialable by hiding between the filter and the suction cups. Went to bed for the night and woke up to find that this one had also vanished. I'm starting to think these fish eat each other when dead?

Anyways, I've just done a test just now and here are the results:
Nitrite - 0
Ph - 6.4 - 6.6
Ammonia - 0
Photo of the test

Somebody has suggested it may be due to there not being enough "good bacteria" and advised adding a dead prawn or shrimp to boost the bacteria build up, but I'm not really convinced.

Any help would be gratefully appreciated!

Thanks in advance,

Andy.

Welcom to the forum!

My first suggestion is that you have a browse in the beginners section and pay particular attention to the 'cycling' threads. This will answer many of your questions (but will also raise quite a few more!). Once you've had a good read then come back here and we'll help you with the specifics.

to the forum, andy, and I'm sorry for your losses.

It is down to not having the beneficial bacteria in your filter. There are two ways of growing this colony; a fishless cycle, where you add either household ammonia or a dead prawn; that provides the food for the bacteria and you wait for them to grow.

The other way, which is what you're doing, is a fish in cycle. In that case, the fish themselves produce the ammonia. Unfortunately, ammonia is very toxic to fish, so you have to remove the ammonia, through lots of water changes, until there are enough bacteria to do it for you. The bacteria will still grow with a level of ammonia that's too small to show up on our tests, but it will be slower than a fishless cycle.

If you click on the link in my sig, you'll find lots of articles that should help you through your first steps in the hobby, but very basically, you need to test the water every day and do enough water changes (making sure the new water is warmed and dechlorinated) so that the ammonia and nitrite (which is what the bacteria turn the ammonia into; another family of bacteria convert the nitrite into nitrate) ever going above 0.25ppm.

Admittedly, it's hard to tell from pictures in a screen, but your ammonia doesn't look like zero to me, and it's almost certainly raised ammonia thats killing your fish.

Don't bother trying to adjust the pH; most fish are very adaptable when it comes to pH; a stable pH is far more important that the actual number.

Best of luck, and do post back if you have more questions; there'll always be someone around to advise you

Fluttermoth got it down pretty much. I know for a fact that what's killing harlequin rasboras is not going to be the pH. Rasboras, tetras, danios, and pretty much 80% of fish in trade that didn't come straight from a river will adjust well to pH, as long as extremes like above 8 or below 5 are avoided. If possible, take the pH formula back. It's better left untouched.

Ammonia however, can kill fish in doses as low as .25 ppm, and on a normal guide to testing ammonia and nitrite, they say to only take action if ammonia is above .25 ppm. Realistically, any amount is stressful and dangerous.

Course of action right now is to do a big water change, as much as you can, but keep the temperature matched to that of the water in the tank. The beginners resource center is your next course of action.

It may be better to switch to a fishless cycle and take the rest of your rasboras back, and get them when your filter is safe, if you're willing to do this.

Alternatively, if you can find anyone who has dirty old filter pads, filter wool, filter floss, filter pretty much anything (except filter water, that's useless) ask them nicely for a bunch of it and stick it in your filter to give it a good jump start.

Good luck

Alot of times when I cant tell if the ammonia test is green or yellow, I pay close attention when I pour it out into the white sink. Alot of times if I think its yellow, pouring it out into a white sink will reveal it's actually light green.

By the looks of the ammonia glass, it seems to be a 0.50 in that picture. A 0 is somewhat golden.

FishBlast said:

By the looks of the ammonia glass, it seems to be a 0.50 in that picture. A 0 is somewhat golden.

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I'd agree, that is ~0.5mg/l ammonia reading, in that scenario I would empty out all but enough water to cover the fish and replace it with similar temp dechlorinated water ASAP.

N0body Of The Goat said:

FishBlast said:

By the looks of the ammonia glass, it seems to be a 0.50 in that picture. A 0 is somewhat golden.

Click to expand...

I'd agree, that is ~0.5mg/l ammonia reading, in that scenario I would empty out all but enough water to cover the fish and replace it with similar temp dechlorinated water ASAP.

Click to expand...

That would also explain why the fish are falling so fast.

I would take the PH Down back and exchange it for a bottle of Seachem Prime dechlorinator. Much better use of your money You have come to the right place to get your tank started the right way.

Welcome to the forum!

Hello all,

Can I just start by offering my gratitude to everybody for their advise.

I made a mistake with my original post, I didn't mean to say that the ammonia was 0, it is/was very much above that level.

I have done a 50% water change (combined with Tap Safe) and seems to have brought the ammonia levels down somewhat, though I'm considering another 50% water change tonight to bring it down to 0.

Am I right in thinking to dechlorinate tap water that I'm okay to use tap safe to do that job?

Tap safe is fine. Any dechlorinter will do the job. I just suggest Seachem Prime because it can make the ammonia and nitrite less toxic which will help them live through your cycle possibly. Keep up the water changes to keep the ammonia at 0. It may seem like a lot of work, but I went through a fish-in cycle when I first started and it's really sad to see the fish suffer.

Quick update. Another 50% changed again and it seems the ammonia level is the same as before (have both tubes side by side). I must have mistook the reading before for being higher than it actually was.

Do you reckon I should check every morning and evening until it stabilises?

andyboot said:

Quick update. Another 50% changed again and it seems the ammonia level is the same as before (have both tubes side by side). I must have mistook the reading before for being higher than it actually was.

Do you reckon I should check every morning and evening until it stabilises?

Click to expand...

Maybe your tap water has ammonia in it too.

Test your tap water. make sure its fully yellow.

Check tap water and make sure your test tubes are cleaned and dryed properly. If not they can give false readings.