Dying fish in stable aquarium

[VSingapore]

Hey fellow Reefers.. although im not a reefer yet, just an aspiring one, I have a freshwater aquarium which I am using to learn ALL (!!) I can about to graduate to a reef so I don't mess up. But now seems that im messing up! Now in the last weeks one by one my fish are dying off.. why??

Fluval Spec 19 liter / 5 gallon freshwater aquarium
Media filter changed out to 50 and 200 filter floss
Seachem Matrix
Seachem Purigen filter media
Charcoal as per original Fluval set

Fully stable tank, set up 3 months ago.
20% water change every second day with bigger water change (50%) once per week. Every time water change by vacuuming substrate with a Phyton.
RO/DI water with added Equilibrium to achieve GH 6 in the tank
Weekly filter floss change with Microbacter top up as per instructions for a stable tank
Rinsing media in aquarium water once per month.
Daily dosing of Flourish excel as per dosing recommendations
Occasional use of Seachen Clarity

Weekly water tests reading in average:
PH 7.30 / EC 400 / TDS 159 / GH 6 / NH3/NH4+ 0 / NO2- 0 / NO3- 0 / ORP 500-523 / Temp 27-29 degrees

Had some fluctuations, firstly when balancing GH it swung from 6 to 8GH on one water change. Now slowly back to 6
Over feeding, very minor Ammonia increase. Proceeded with water change and added Zenolit filter (volume as per packaging instructions). Balanced back to zero in a few weeks. Zenolit removed.

In tank I have (had)

1 x male betta
1 x female betta (died - see pic)
6 x tetra ( -1 died, stomach turned black when dead)
2 x some type of slim gold fish looking (both died - one heavily bullied, no tail left. Second died shortly after for no apparent reason)
1 x alge eater
2 x sword tail
1 x snail (died)

It all started when introduced the two "gold fish". For from a fish farm, netted by the kids in a pond. One was heavily bullied by the swordtail and died after two weeks. Parts of tail missing hence suspecting it was from the bullying.
Second "gold fish" died two days later for no apparent reason.
Betta died two weeks after that. Lethargic for 3 days, didnt eat. Died
Tetra died one week after that for no apparent reason. Black stomach when dead.
Snail died one week after that, no apparent reason.

All fish removed within hours of dying. Somehow I suspect that the "goldfish" brought some illness, but the deaths are spaced out by weeks. Also all remaining fish are happy, healthy and active.

Please help? What am I doing wrong?

 

[Mr. Mojo Rising]

Gold fish are cold water fish as far as I know and put into a tropical water tank I don’t think they would do well.

 

[VSingapore]

Gold fish are cold water fish as far as I know and put into a tropical water tank I don’t think they would do well.

Indeed. Actually its a freshwater tank I have. Using it to learn all I can to move into marine tank

 

[monkeyCmonkeyDo]

Betta are very aggressive and territorial fish? I believe they are suppose to be kept single.
Idk nothing about fresh water sorry. Your on a ford site asking about chevys.
D

 

[VSingapore]

Betta are very aggressive and territorial fish? I believe they are suppose to be kept single.
Idk nothing about fresh water sorry. Your on a ford site asking about chevys.
D

haha.. yeah totally agree on the car dealership. Indeed Bettas are territorial but there is peace in the tank in general. Enough space, hiding places and carefully chosen tank mates.

 

[Robertellis30]

Betta’s are only aggressive towards Betta’s.

best thing I can say to do with a freshwater tank is follow the KISS method. Don’t over think it. Do your water changes and maintain maintenance on the the filter.

also I would stay away from gold fish. There dirty fish that muck everything up an algae eaters get aggressive.

 

[VSingapore]

Betta’s are only aggressive towards Betta’s.

best thing I can say to do with a freshwater tank is follow the KISS method. Don’t over think it. Do your water changes and maintain maintenance on the the filter.

also I would stay away from gold fish. There dirty fish that muck everything up an algae eaters get aggressive.

You know you are right. My husband is holding me hostage to succeeding with the freshwater tank in order to "allow" me to get a marine tank.. arghhh.. He keeps on stating that I change water too often but I don't believe im doing damage with that given RODI water and parameter staying stable. Thank you for your support and encouraging words..

 

[UnderseaOddities]

They can do well in warmer water just won't get as large... My money would be on the betta most are sold in tap water in small cups of water unless you go to lfs,(my lfs has 20 1 g betta boxes on a wall for 20 to 40$ a piece) alot of the aquarium experience is know where your animals come from and how they were taken care of I went to my petco today for dog food every fish in the store had ich no joke,fresh and salt, salt had every algae you could think of 10 dead nems and 4 dead fish brooklynella euronema and velcet( bicolor angel, 2 kupangs and an orchid dotty back) filtration was only workeing half way fish were gasping for air.. 50 cups of bettas 39 of which were dead this is just unacceptable.

My 2 cent quality in quality out know the who what when where why when it comes to your fis,h even if it means paying a little more or taking a drive and always qt, since you're in freshwater you can even dose copper based bottles to display tank to stop any parasites, bacterias or illness in they're track, just make sure the oxygen level is sufficient enough as copper deoxygenated the water

Or you can go the other route and do what I do and a lot of other people do and spend a few bucks on a sterilize tote or aqueon 10 20 30 40 55 or 75(whatever's cheap and practical) and setup a hospital tank ( called qt for quarantine tank) run your filtration and an airstone, I personally like to QT for a month or so sometime it can take longer situation dependent. I use praziquantal then formalin and then when they clear up or start eating or whatever the case was that they were in qt in the first place the fish will then get moved to where it needs to go only after the initial process is complete

 

[Mariette]

5g tank w that many fish is a major bio overload. Daily water changes help keep ammonia down but the amount of water changes set out in your post suggests no time to allow beneficial bacteria to grow and stabilize a tank. Plus you have a few fish in there that shouldn’t be in such a small tank. Swordtail for example. 2 betas is a bad idea too. Male will harass the female and may even kill her after mating. Goldfish are cold water fish and also carry a disproportionately high bio load ie they eat and poop a lot. Cramped conditions. Too many water changes. Fish on fish aggression. You’ve created a stressful environment ideal for the transfer of disease. I myself have made a TON of mistakes so I’m certainly not judging. Get it to a point the tank can maintain itself w weekly water changes of 25% or so. If ammonia is spiking, reduce bio load.

 

[VSingapore]

5g tank w that many fish is a major bio overload. Daily water changes help keep ammonia down but the amount of water changes set out in your post suggests no time to allow beneficial bacteria to grow and stabilize a tank. Plus you have a few fish in there that shouldn’t be in such a small tank. Swordtail for example. 2 betas is a bad idea too. Male will harass the female and may even kill her after mating. Goldfish are cold water fish and also carry a disproportionately high bio load ie they eat and poop a lot. Cramped conditions. Too many water changes. Fish on fish aggression. You’ve created a stressful environment ideal for the transfer of disease. I myself have made a TON of mistakes so I’m certainly not judging. Get it to a point the tank can maintain itself w weekly water changes of 25% or so. If ammonia is spiking, reduce bio load.

Hmm.. appreciate your thoughts! Indeed I need to change things around and you make a good point. Just on the water changes.. can one do too many in a tank that is "stable"? Or I don't have a stable tank as my measurements artificially return good readings as I put in new water every second day?

 

[VSingapore]

They can do well in warmer water just won't get as large... My money would be on the betta most are sold in tap water in small cups of water unless you go to lfs,(my lfs has 20 1 g betta boxes on a wall for 20 to 40$ a piece) alot of the aquarium experience is know where your animals come from and how they were taken care of I went to my petco today for dog food every fish in the store had ich no joke,fresh and salt, salt had every algae you could think of 10 dead nems and 4 dead fish brooklynella euronema and velcet( bicolor angel, 2 kupangs and an orchid dotty back) filtration was only workeing half way fish were gasping for air.. 50 cups of bettas 39 of which were dead this is just unacceptable.

My 2 cent quality in quality out know the who what when where why when it comes to your fis,h even if it means paying a little more or taking a drive and always qt, since you're in freshwater you can even dose copper based bottles to display tank to stop any parasites, bacterias or illness in they're track, just make sure the oxygen level is sufficient enough as copper deoxygenated the water

Or you can go the other route and do what I do and a lot of other people do and spend a few bucks on a sterilize tote or aqueon 10 20 30 40 55 or 75(whatever's cheap and practical) and setup a hospital tank ( called qt for quarantine tank) run your filtration and an airstone, I personally like to QT for a month or so sometime it can take longer situation dependent. I use praziquantal then formalin and then when they clear up or start eating or whatever the case was that they were in qt in the first place the fish will then get moved to where it needs to go only after the initial process is complete

Yes you are absolutely right!! I thought to myself that I should quarantine the new fish but didnt have a QT set-up and didnt know where to go to get them housed (i.e. shop that offers such services). Lesson learned for sure.

 

[UnderseaOddities]

It doesn't have to be expensive yo can use a 10 g or larger tote full of water anyone can qt

Yes you are absolutely right!! I thought to myself that I should quarantine the new fish but didnt have a QT set-up and didnt know where to go to get them housed (i.e. shop that offers such services). Lesson learned for sure.

 

[MmeAssoc]

e by one my fish are dying off.. why??

Hey, I have the same tank - I'm keeping a single male betta, plus a lot of plants.

Your betta will like limited flow, particularly if it has long fins (I put a sponge over the filter output to keep the water flow low).

It's hard to keep betta with other fish, particularly in a tank that small. I used to have a few pygmy corydoras in mine as well, but it seems that even that small bioload was too much for the tank.

I'm also not sure you need to be changing that much water, especially if your nitrates are constantly at 0 - I do about 1/4 of the volume once every week or fortnight.

* edited to remove comment about heater - I can see your temperature looks good for most tropical freshwater fish.

 

[Mariette]

Hmm.. appreciate your thoughts! Indeed I need to change things around and you make a good point. Just on the water changes.. can one do too many in a tank that is "stable"? Or I don't have a stable tank as my measurements artificially return good readings as I put in new water every second day?

You can absolutely do too many water changes. With such a high bio load, you have no choice really. But your stripping the tank of all the natural bacteria that fish need to be healthy. I wouldn’t think your tank is stable at this point.

saltwater tanks in particular will need to be properly cycled and tested to ensure stability prior to adding anything alive to the tank. Once cycled, you can restart the cycle by doing too many or too big a water change. You’re definitely gonna want to avoid that mess in saltwater tanks. Trust me. I speak from experience lol

 

[VSingapore]

It doesn't have to be expensive yo can use a 10 g or larger tote full of water anyone can qt

Yeah will do. I only hesitated as I need to have it cycled first hence a running system on standby.. right? Or can I just pop RODI water in there and use it for QT on short notice?

 

[VSingapore]

You can absolutely do too many water changes. With such a high bio load, you have no choice really. But your stripping the tank of all the natural bacteria that fish need to be healthy. I wouldn’t think your tank is stable at this point.

saltwater tanks in particular will need to be properly cycled and tested to ensure stability prior to adding anything alive to the tank. Once cycled, you can restart the cycle by doing too many or too big a water change. You’re definitely gonna want to avoid that mess in saltwater tanks. Trust me. I speak from experience lol

I see. I will stop the water changes and revert to weekly. I imagine I should see a spike as it will start to cycle? Will also rehome some fish

 

[VSingapore]

Hey, I have the same tank - I'm keeping a single male betta, plus a lot of plants.

Do you have a heater? Your betta will like the water kept around 25C, and also limited flow if it has long fins (I put a sponge over the filter output to keep the water flow low).

It's hard to keep betta with other fish, particularly in a tank that small. I used to have a few pygmy corydoras in mine as well, but it seems that even that small bioload was too much for the tank.

I'm also not sure you need to be changing that much water, especially if your nitrates are constantly at 0 - I do about 1/4 of the volume once every week or fortnight.

My temperature stands at 27-29C, I live in a country where I would need a chiller rather than a heater haha. (i.e. Singapore).

Indeed water flow is a bit of any issue for the Betta. I keep the flow at a minimum but without a sponge as im keen on getting water running through the system. Would a sponge significantly reduce the amount of water that circulates in the system?

 

[Mariette]

I see. I will stop the water changes and revert to weekly. I imagine I should see a spike as it will start to cycle? Will also rehome some fish

Your going to want to keep an eye on the ammonia when you cute back on water changes. If it spikes, you have no choice really. Definitely rehome some fish or better yet, upgrade to a bigger tank and get more fish

 

[VSingapore]

In a separate post I read that snails + fish dying is a sign that its not disease but rather contamination. So all evidence is pointing to an unstable tank?

 

[UnderseaOddities]

In freshwater the key to a good system is a a working symbiosis at first on a bacterial level
Then biological (sand dirt gravel rocks plants) mechanical ( filtration lighting ) chemical( food bottles dosed) for freshwater I like to do soil then sand then gravel for the media 2 in thick for finite cheating of organic inputs( more surface area = more bacterial growth/colonization then rock work... Most aquarium stores want us to do it backward and have filtration at the top... Yes movement and filtration at the top of the tank are important but a good substrate is sometimes overlooked in freshwater and thought to only be detrimental in salt. We can borrow many techniques from takashi amano of ada japan and the idea of a balanced system by using rule of 2/3rds 1/3rd substrate 1/3 rockwork and plants 1/ 3rd water.

Also here's a video from the fish sage

Father fish.