Betta fish just died, what could've been the cause of death (info inside)?

[AWE]

Hello to all!

Sadly, my Betta fish died a few hours ago and I am really not sure why so I'd like the more knowledgeable to give me some advice, I really want to prevent this from happening in the future.

- The tank is a 60l (approx. 15 gallons) planted one and it's equipped with an Eheim heater set to approx. 80 degrees Fahrenheit and a Sera Fil 60 filter;
- Aside from the Betta male, there are also 4 neon tetras and a 2 Cory in the tank (they never fought or something and the Betta was actually ignoring them all the time), all added more than 1 year ago;
- The Tank is in use for approx. 2 years now and there were no recent issues except for 1 neon and 2 Cory which died unexpectedly 6 months ago (most probably due to a filter malfunction which was not detected in time, filter was subsequently replaced);
- No fish or plants were added recently;
- Water changes of approx. 25-30% are done every week and I always test the water parameters, no issues that I've found
- I didn't overfeed them, even skipped food for one day once in a while;
- The Betta was approximately 1.5 - 2 years old at the time of death.

I'll try to upload a picture of him from yesterday as well. Regarding the symptoms, he started hiding in plants or decor for the most part, stopped eating completely but was otherwise swimming normally when he went to the surface to get some air but then immediately returned to a passive state, hiding. Its condition worsened in the next days, I tried treating him for (suspected) parasites, doing water changes and adding some vitamins to the water (Sera Fishtamin) but it didn't help...

Any advice from you would be very welcome! Thanks in advance!

 

[Colin_T]

Hi and welcome to the forum

If the water is good (0 ammonia, 0 nitrite, nitrate less than 20ppm and pH around 7.0) then the fish in the picture either died from a protozoan infection or bacterial infection.

The fish in the picture looks like it has a few scales sticking out around the belly and that is indicative of an internal bacterial infection. The discolouration on the rear half of his body also suggests a bacterial infection.

The Betta might have been old and his immune system was probably not as good as it was when he was younger, and he might have picked up or developed an internal bacterial infection.

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How often do you clean the filter and how do you clean it?
Filters should be cleaned at least once a month and every 2 weeks is great. If you have a power filter you should wash the filter materials in a bucket of tank water, then clean them in a second bucket of tank water. After that put them in the tank and wash the filter case and motor. Reassemble the filter and get it running again.

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I would increase the size of the water change to about 75% each week rather than 25-30%. Fish live in a soup of microscopic organisms and these can build up in numbers and affect the fish. Bigger water changes help to dilute these organisms much more effectively than small water changes. You should also gravel clean the substrate when you do a water change.
Make sure any new water is free of chlorine/ chloramine before it is added to the tank.

 

[Sarah73]

My question is what do you mean by good water parameters? That is a long time in captivity, so likely died of old age. As for your stocking it's not the greatest, but if you want to talk about that then we can.

 

[TallPaul]

It could really have just been old age. 2 years is reasonable for a betta fish although some can get as old as 5. In the wild they barely live for a year.

Unless you know exactly where he was brought in from and how old he was when you got him it's hard to say.

Personally I would not replace him with another betta seeing as you have 4 neon tetra already. Would you consider adding more neons. They do best in large groups.

Use aqadvisor and input your dimensions and filter to see what kind of stocking capacity you can have.

 

[Sarah73]

It could really have just been old age. 2 years is reasonable for a betta fish although some can get as old as 5. In the wild they barely live for a year.

Unless you know exactly where he was brought in from and how old he was when you got him it's hard to say.

Personally I would not replace him with another betta seeing as you have 4 neon tetra already. Would you consider adding more neons. They do best in large groups.

Use aqadvisor and input your dimensions and filter to see what kind of stocking capacity you can have.

Aqadvisor is rubbish. Don't ever use it.

 

[TallPaul]

Aqadvisor is rubbish. Don't ever use it.

Really.

I don't swear by it but I find it isn't too bad at calculating stock sizes.

I did notice that it does not recommend putting amano shrimp in with my betta but I know that tonnes of people keep non fish critters with no problem at all.

 

[AWE]

Thanks for the answers! So, 0 ammonia, 0 nitrite, almost no nitrate (10 ppm or so) and pH around 8.
I clean the filter with tank water every 2 or maximum 3 weeks and when changing water I also siphon the gravel every time.
The Betta was not that old, not even 2 years I think...
I know the stocking is not the greatest but it was a surprise acquisition made by my daughter, she bought the fishes without saying anything while on holiday at her grandma's and we decided to keep them... Long story...
Now if it was a bacterial infection issue, what steps should be taken to ensure the rest of the fishes are safe?

 

[TallPaul]

A pH of 8 isn't ideal. Betta prefer their water softer than that really, 7.0 or a tad lower. Higher pH levels can cause issues with their fins.

Is the water always at 8.0? If so then that probably isn't a problem, they can cope in that water. It's only when there are swings in pH levels that they can suffer on shock.

 

[AWE]

The pH is almost always close to 8, yes. I know that it should ideally be around 7 or so but I haven't had any issues because of that so far...

 

[Colin_T]

Now if it was a bacterial infection issue, what steps should be taken to ensure the rest of the fishes are safe?

Do a 75% water change and gravel clean the substrate each day for a week. Then monitor the remaining fish and if they show any unusual colours or damage to their fins or bodies, post a picture of them immediately.

Don't bother about the pH.

 

[AWE]

A 75% water change EACH day for a week? Wouldn't this de-cycle the tank?

 

[Colin_T]

Doing a big water change each day will not affect the filter bacteria. You can do a 90% water change each day if you like and the filter bacteria will be fine.
Make sure any new water is free of chlorine/ chloramine before it is added to the tank.

The water changes dilute nutrients and microscopic organisms in the water, whereas the beneficial filter bacteria live in and on filter materials and hard objects in the tank (driftwood, gravel, etc). But most of the good filter bacteria live in and on the filter materials.

The reason for doing a big water change each day for a week is to dilute any bad bacteria or other diseases in the water and reduce the chance of the other fish developing the same issue that killed the Betta.

 

[Jack TH]

Where did you get him from? If you got him from a chain store then 2 years is honestly a pretty decent lifespan. There are stories of them living up to five years, but 2-3 years I'd say is the average. Your estimate is pretty rough, so you're obviously not sure on exactly how old he was. If he was fully grown when you got him then there's no way to tell, so for all you know he could have already been 18 months old or more. If he wasn't though, then he was almost certainly less than a year old, probably no more than about 6 months. Honestly unless other fish start showing symptoms of anything there's no reason to believe an illness killed him. Until then though you should follow what Colin has said, just to be safe.

As a side question, do you live in the UK? Over here, or at least in the South East, we have tetras that are unbelievably strong. They are nearly indestructible. While all my guppies were dying of various diseases, my tetras at the time were thriving and had never been better. My black neons exploded in size. When I got my batch of glowlights, they all had pretty bad fin rot. A lot of them had very stubby and almost non-existent dorsal fins. They must have some reptile DNA because they completely recovered from it within about 3 weeks with no treatment whatsoever. I've never seen fish with such strong immune systems. On top of that, I didn't even drip acclimate them. I never lost any except a green neon. Everybody else survived and if it wasn't for me giving them back to the fish store when I wanted to focus on guppies again, I have no doubt they would all be alive now.
So if you do live in the UK, or even better the South East (somewhere like Kent or Sussex), you probably have nothing to worry about with your tetras. They are ridiculously hardy and completely defy the common tetra stereotypes. All the while the guppies are fragile, weak disease bombs.

Sorry to detract from the topic of your thread, I just wanted to make that point about tetras. Sorry for your loss, it's never nice to see one of your finned friends move on

 

[AWE]

@Jack TH: First of all, thank you for your kind words. I'm also thanking everyone who's posted in this thread. That Betta was a fish I've really cared for and I've considered him (yes, HIM) a friend all along the way.
Back to your question: We've got all fish from a reputable seller, maybe it's the reason for not having major problems with them for quite some time.
As a side note, I'm not living in the UK but I'm still living in Europe. I've also noticed that tetras are indeed hardy fish and they would probably survive a lot of things before they give up. Now I've noticed that my Cory has become a little less active than it used to be, going to do some water change and watch how things develop. Still not sure how some bacteria or anything else can affect a habitat since nothing has been changed in months, no other fish or plant has been added and the environment hasn't changed in many months (same water source with same parameters, same everything).

 

[Colin_T]

Still not sure how some bacteria or anything else can affect a habitat since nothing has been changed in months, no other fish or plant has been added and the environment hasn't changed in many months (same water source with same parameters, same everything).

Fish live in a soup of microscopic organisms ranging from bacteria, viruses, protozoa, fungus, flukes, worms, etc. Some bacteria, virus & fungus spores can drift in the air and land in the water and grow from there. Other organisms (protozoa, flukes, worms and different bacteria) need to be introduced into an aquarium with new fish, plants, shrimp or contaminated water or contaminated objects.

Fish can also have these disease organisms on them in low numbers and remain fine for months or as long as the fish is strong and healthy. However, if a fish gets run down, or its immune system becomes weaker, then the disease organisms in the water can take over and adversely affect the fish.

Doing small water changes (20-30%) on the tank will only dilute 20-30% of these microscopic organisms and leaves a lot of them behind where their numbers can rapidly build up. Doing a bigger water change (75-90%) dilutes the organisms much more and leaves fewer behind to infect the fish. It also takes longer for the disease organisms to build up in numbers after they have been diluted by such a large amount.

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As an example, most aquarium fish carry gill flukes and intestinal worms in low levels. The fish can easily live with these parasites because there are only a few of them and they don't do too much damage to the fish and don't take too much blood from the fish.

If the fish gets old or stressed out by something, sudden temperature change, scared or startled by something, missed a meal or got some bad food, or the water quality deteriorated for a short time, the fish's immune system could struggle and the fish becomes sick or gets run down. When that happens the other types of microscopic organisms in the water can get onto the fish and make them sick. When that happens the fish's immune system is overwhelmed and the fish cannot deal with all the things attacking it. Then we have to treat the fish and kill off the disease organisms, or the fish dies.

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Other things can impact on fish and animal's health, including what they were exposed to at a young age. If the fish was exposed to chemicals (fish medications or other types of chemicals) before you got it, that could have done some damage to it. If the fish was in poor water quality before you got it, that would also do some damage.

This damage does not show up as ripped fins or funny body colours. It occurs inside the fish, in their organs and their cells. It is cumulative and each time the fish is exposed to something bad, it adds to the load in the fish. This means the fish can be weaker than other fish that have not been exposed to the same stress factors.

Fish that have been exposed to poor water quality (ammonia, nitrite, nitrate, incorrect pH or GH), or wrong temperatures, or malnourishment will have a shorter life and have more chance of being affected by diseases than fish that were kept in ideal conditions and fed well from the day they hatched.