Fish randomly dying, not sure why - Tropical Fish Keeping - Aquarium fish care and resources
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post #1 of 24 Old 03-10-2011, 11:46 AM Thread Starter
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Fish randomly dying, not sure why

My wife and I have a 20G freshwater tank setup. I added the water and the water clarifier with the tank and let it cycle that I'd say for about a week. Then my wife went to Petco, and purchased a few fish (I originally wanted glowfish and the little ones with glowing stripes, but they didn't have any, so she came home with 4 black mollies, 4 of these angelfish little guys, 2 swordtails, 2 of these white fish, and 2 of these larger orange guys. Sorry, she doesn't know the names either.


after adding them, next day, one black molly was dead. Figured it was the shock... then one of the larger orange guys was having problems swimming properly, was stuck in a plant at one point and just never recovered. It appeared he might have been also bullied by the one swordtail. Then two different days the white guys died. Another black one died this morning and I swear when I turned the light on the tank this morning, both swordtails were swimming around, but then I looked and saw one of them dead. Could the sudden light turn on have killed him? What would have killed the others?

All of these fish were swimming around the night before pretty good. They're eating tropical flakes and all. I don't see any sort of skin discoloration to them. I have one big "fake" tree log in the middle for them to swim in and out of, some grass throughout, a filter, and an air pump since they needed more oxygen in the tank.

I tested the ammonia level the other night with the Ammonia Quick Dip by Jungle and it appeared to come up normal. Honestly, I was told not to worry about pH but more so ammonia. I was also told I didn't need to add any sort of bacteria to the water. We live in Hawaii and the tank temperature is constantly around the 77-78 F mark. How often does the light above the tank need to be on?

What am I missing here. I know I'm new to this and thought we were doing everything right, but what's my next step?

As of right now, all the other fish are swimming around fine. None of the angelfish little guys have died... maybe theyre more hardier?

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post #2 of 24 Old 03-10-2011, 11:55 AM
bearwithfish's Avatar
wow so much to throw out there for information... but lets go slow ...
1st your tank was not cycled in a week (that was just bad information yo received) here is a good link

read that first

2nd way to much stock way to fast.... here is another good read

hope this info starts you off good and others will jump in shortly to help also Good luck and welcome to TFK!!!!!!!!

Back in the Game!!! Live Bearers in a 40 Breeder
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post #3 of 24 Old 03-10-2011, 12:10 PM
Yeah that tank is not cycled. I would suggest taking all the fish back and doing a fishless cycle. The angels for example are not likely to survive the cycle.
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post #4 of 24 Old 03-10-2011, 12:27 PM Thread Starter
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Thanks for the quick responses. I really appreciate it.

Just some other questions then:

Is it right to just test for ammonia levels, or should I have a strip that tests for everything?

How often do the fish need the light above the tank on?

Thanks again,
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post #5 of 24 Old 03-10-2011, 01:11 PM
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personally i hate strip tests they can go bad very fast and often the moisture in the air will alter the reading on you. i would get a good drip test kit (i like API) and go with that at first you sold test for PH, nitrate and nitrite, dKH and after you determine your water type it will be easier to determine what you need for conditioner, what fish will thrive well in your water type and if you are attempting to alter the water to accommodate a specific type of fish you can look at methods to do that as naturally as possible.

Back in the Game!!! Live Bearers in a 40 Breeder
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post #6 of 24 Old 03-10-2011, 05:23 PM
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Welcome Matt and Wife! We're so glad you found us! First let me tell you that every one of us in here has been in your shoes and lost new fish!! Second shame on the LFS Local Fish Store for giving you bad advice on two things. Yes you need bacteria, and selling you all those fish that would upset any established bacteria load.
So... a lot of things have been covered already, and you are going to read, read, read... right? I'm going to touch on a couple of basics not yet discussed, you may already know of some of this but just in case.
Your fish yes have suffered from shock and it comes in different ways but is quick.
All water needs de-chlorinator/conditioner to remove chlorine, every bucket, every water change. You will be doing minimum 20-30% weekly water changes, unless other issues arise, but this is basic care. Get a calender and write down what you do on what day, as time goes by and you forget when you last did something, or added someone to the tank.
Get a thermometer if you don't have one. Every bucket added must match the tank temperature.
Get a Liquid test kit as metioned in the previous post.
Test weekly at the least before and after your water change. Know your numbers always for ammonia and NI and NA.
When you have cycled the tank, and have good bacteria or bio load, (6-8 weeks) then you can add fish slowly. Even a large tank like mine at 75Gal , I cannot just go get 15 fish and add them, as the bio load is not sufficient to support that much of a change, and fish will die.
When new fish are added, float the bag in the water for 30-45 minutes and dribble littles amounts of TANK water into the bags every 5 minutes or so. You will equalize the temps and also acclimate the fish to any change in PH. We do not recommend changing the PH but it is important to know what kind of fish do best in what PH. Eg, my 8.2 PH in Ontario would kill Discus that need 6.5 - 7. so I have to look at African Cichlids or something locally raised in my area's water and slowly blend them over entry time.
When the time is up, you should have doubled the water in the bag and net the fish to put them in.
Lighting is important because fish need a natural fluctuation of light just like we do. As natural as possible. Get a inexpensive timer / power bar for your tank and set it to generally no more than 8 hours of light. Light can raise the tank temperature excessively, and cause huge amounts of algae. Setting the timer means less chance to overdo it. If you like to watch your fish till 11pm then set it to come on 3 pm, off at 11, and the rest of the time it just gets ambient light.
When you do finally add more fish do so 2 ish at a time. do it slowly as you currently do not have the good bacteria present. You need to keep building the good bacteria to support that many fish.
So lots to learn. Ask lots of questions! and after 15 posts come look for others in the chat room where we can talk live. Good Luck.

Every kid, regardless of what they are going through, is ONE caring adult away from being a success story. ~ Josh Shipp, Teen Behavior Expert
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post #7 of 24 Old 03-10-2011, 09:19 PM Thread Starter
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Thanks again for the input.

We are heading out tomorrow to get a liquid test kit (what specific one is recommended)?

Also with a 20G tank, how many fish can we house comfortably without cramping or having them fight once the tank is properly cycled?

Also, what brand bacteria should I be looking into adding to the tank?

We did add clarifier/dechlorinator to the tank to let it cycle within the first week. When I mean cycle, I'm just referring to it filtering through the pump.
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post #8 of 24 Old 03-10-2011, 10:05 PM
Just a quick (but important) clarification for you regarding the "cycle", it is in reference to the biological maturing of the tank. I'm new to tropical fish as well, but the cycle that everyone is referring to is the ammonia being produced and peaking, then nitrites being produced and peaking, and finally nitrates being established in the tank. This whole cycle takes several weeks (month to 6 weeks) for the water to be safe for fish. There is a lot of good information on this site to better explain to you exactly what "cycling the tank" means. It is not in reference to the water being pumped through the system.

Don't give up. It's difficult to have fish die on you, but the more you learn, the better you will be able to take care of your fish.

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post #9 of 24 Old 03-10-2011, 10:14 PM Thread Starter
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After the reading of that cycling article, I better understood it. I'm learning more than ever. I remember in the past as a kid, I had goldfish, but you know how those guys do when watched for by kids.
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post #10 of 24 Old 03-10-2011, 10:17 PM
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