Excessive Fish Loss

  • #1
Alright, I thought getting some fish for my daughter to watch would be a good idea but it has turned out to be a complete disaster because they keep dying! 10 fish have kicked the bucket in total and I have no idea what to do now, so I'm hoping that folks with a little more experience can give me some suggestions. I'm about ready to just give up on the whole endeavor but would really like to see this thing thrive for her.

We have a 10 gallon aquarium that we picked up brand new several months ago. New aquarium gravel was washed and put in and the tank was fully cycled. The water in our area is extremely hard (8.3 pH level), so we opted to go with Mollies since they're very hardy. We initially got 3, waited a week for the tank to catch up to the load, and then added 3 more, giving us 6 fish in there. The ammonia and nitrate levels were initially a little high but we managed to get those under control; one died during this time, likely because of the high ammonia levels so I wasn't too surprised by that. Since then, we've had a large number of deaths. Two or three more died all within a 2 day period when ammonia, nitrate, and nitrite levels were all reading 0. Another died about a week later. We got 4 more fish a few weeks later after seeing nothing else dying; this brought us back up to 6 fish. I have been careful to keep the female-to-male ratio at 2:1 so that the females are never over-stressed by the males during the entire period. Over the stretch of the past 3 months or so, 5 of those 6 have slowly died off, leaving us with a single fish. When the last male died, there were only 4 females in there, so they definitely weren't being over-stressed by any males. It's not terribly interesting to watch that single fish on her own and we're starting to wonder if we're just going to lose that one as well. The fish have all come from a reputable, locally-owned pet store that stocks countless variety of fish and have been around for 40+ years.

At one point we had a small rubber nose pleco but he up and died as well. Two snails snuck it in at some point (presumably from one of the fish stocks). They did a good job at cleaning for a while but they over-populated and died from a lack of food.

We have a single, small-ish piece of driftwood in the aquarium and a ceramic hollow log for them to swim through. Ammonia, nitrate, and nitrite are still reading 0. Water pH is still a seemingly harsh 8.3. All of those readings were done with the API liquid testing kits (not the strips). The water temperature is between 72F and 74F using the little heater that came with the aquarium (that's being measured by one of those strip thermometers which are stuck out the outside of the tank and I find it hard to believe that it accurately reads the water temperature from the other side of the glass). Filter has been replaced once a month since having it. Weekly water changes have been about 25%. API freshwater aquarium salt has been used according to its directions. I've also used a water conditioner (can't remember the name) according to its directions of 2 drops per gallon of water added during changes. Feeding of flake food has been 6 days with food and 1 day without food per week. The aquarium lights are on for 12 hours per day (9am - 9pm) but they can get natural daylight outside of those hours depending on the season.

I've tried using SeaChem Neutral Regulator powder to reduce the water's pH level but that has done virtually nothing.

I'd have though mollies would have been able to survive in this pH level. Is that right or do I need to change fish? Am I overfeeding? Wrong water temperature? Not changing enough water? Do I just clean the whole thing out and start the cycle all over again? Or am I simply cursed by the fishy gods?

Any help would be greatly appreciated. I'd like to see something live in this tank for more than a month or two.

  • #2
Welcome to fishlore!
The first thing you need to do is read about the nitrogen cycle. Because I believe that is your biggest issue here. You never cycled the tank. And every time you replaced the filter, you started the tank from scratch.

Once you read about the nitrogen cycle, then we can help you cycle and stock the tank properly So you don't have to continue to deal with constant deaths.

Ohio Mark
  • #3
Welcome aboard! Bizaliz3 is right... You've had a rather discouraging start, but there's lot of held & advice available here.
  • #4
Hello krudolph! Welcome to the forums!

Thank you for adding so much info. Usually people tend to leave out valuable information.

I see a few issues here. Cycling, parameters, and stocking. Any of these can lead to the death of your fish.

First off stocking. I highly suggest to any beginner never to get both males and females of molly, guppies, or platty. They will reproduce up to hundreds of fry in their lifetime. I always suggest getting only male fish for these species because they can come pregnant from the store. Females can hold sperm for up to 8 months with no Male contact.
There are no plecos that are small enough for your tank. The smallest breeds need a 30 gallon minimum. However, you can look into nerite snails (can't reproduce in freshwater and come in cool shell patterns) or shrimp (ammano shrimp, cherry shrimp, etc) when your tank is more established.
If i'm remembering correctly, Mollys need 30 gallon minimum tank size. There's a 10 gallon stocking list on the forum with tons of options! A personal favorite of mine would be celestial pearl danios. You can also use an aqadvisor as a general guide (dont take it to heart). We also have lovely forum members here who are pros at stocking. You can post a thread in the stocking section.

Next off cycling.
How did you cycle the tank? My suggestion to you is to get janitorial pure liquid ammonia and a little eye dropper & do a fishless cycle. This way, you know your tank is cycled and no fishy deaths! Plus you'll learn a ton about cycling and water parameters along the way. I suggest dosing the tank to 2ppm ammonia and keeping it there until it can process to nitrates in 24hrs for a few days before adding fish.

Your parameters are not good or showing signs of cycling and I'll get to why in a second. But first, a fully cycled tank should show 0 ammonia, 0 nitrites, and 5-20 nitrates. Because you are showing 0 nitrates, this shows your tank is not cycled. From reading your info, you've stated that you replaced the filter every month. This actually is what killed your cycle. Never listen to the filter box. You should never replace your filter media unless it is falling apart or unable to come clean. The companies just want you to spend tons of money on filter media so they can get rich. You should clean your filter once a month to start and eventually guage if you need to do it more often or less often based on how dirty it gets. Some of my tanks I only need to clean every 3 months and others every 2-3 weeks. To clean a filter, unplug it. Take out all of the sponge or floss media and shake/squeeze it in a bucket of old tank water from your water change or in a bucket of dechlorinated tap water. Then replace. You can also clean the inside of the filter housing itself with a toothbrush. The beneficial bacteria that converts toxic ammonia and nitrite into less toxic nitrate lives inside the media of your filter. So by replacing it, you're starting all over and needing to cycle your tank all over again. Also, beneficial bacteria will also die in 24-48hrs with no ammonia. So the days/weeks between fish will kill off the bacteria if you don't dose ammonia.

We all started off rough and most of us were lied to by fish stores and succumbed to many fish deaths. But with time, fish tanks can become amazing and fun! Keep up all the hard work and don't be afraid to ask us anything.

Also, I highly suggest looking into a python water changer and biomedia (ie bioballs, ceramic media, etc) for your filter to help keep a cycle. Esp in case you need to replace a cartridge down the line. I also suggest to up your water changes to 30-40% weekly. With hardy fish I tend to do 40-50% weekly.
  • #5
Novice fish keeper here, so not much advice to offer outside of how I personally dealt with my ph.
I have high ph water (about 8.6) as well and I also experienced some random fish deaths when I first started out. I lost quite a few that I had gotten from my local pet store.
I attributed it to pet store quality fish and high PH (and probably my own ignorance).
Going forward I added peat moss to my filter, driftwood and almond leaves, all of which have helped lower my ph to a more acceptable range (it sits around 7.6-8 depending on how old the leaves are and if ive changed the peat moss etc). I also purchased fish from an online source in the hopes they were better quality and so far I haven't lost any more fish. In fact my guppies have graced me with babies many times over..

So yeah, that's what worked for me in regards the getting my ph down. Maybe it will help you too. I know its discouraging but just hand in there! when you get it right its such a good feeling!
  • #6
Welcome to Fishlore...

I am sorry to hear about your rough start. You have come to the right place to get the help you need to get this tank on track and finally get to enjoy the hobby.

I agree, I don't think this tank ever completed its cycle but we can talk you through that.
  • #7
The first two things everyone should do is. Cycle the tank. Get a API liquid test kit to check the reading. Ammonia and nitrite should be zero and you should have some reading of nitrates for the tank to be completely cycled. Don’t ever rinse filter, gravel etc in tap water. Use only treated tank water.

Second, quarantine every new fish before adding to an established tank. As new fish may carry diseases etc.

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