Are Figure 8's brackish or freshwater?

[GallonsOfFun]

They are freshwater in the wild but many claim that they live longer and have stronger immune systems in brackish water. I work in research and I'm a little skeptical of this claim; I'm not saying it's wrong, I just want to hear the reasoning/evidence behind it.

They are primarily freshwater in the wild which would make it surprising if their bodies were somehow better suited to brackish water. Evolutionarily speaking, that seems unlikely. I'm worried that the claims of them living longer and being healthier have originated from one persons anecdotal evidence and was subsequently accepted as fact by the internet world (ie. I had this puffer in fresh and this one in brackish, and the brackish one lived longer so it must be because of the brackish water - this evidence isn't reliable). Can someone clear this up for me?

 

[Nils]

I have personally never heard of any completely freshwater figure 8 puffers. Only completely freshwater ones I know are dwarfs, fahaka and amazon puffers.

I guess people say that there are completely freshwater ones because of where they live. Lets say we have a river that goes into the ocean at the end. The side closest to the ocean will be brackish because that's where freshwater and saltwater mix. The side that is a bit farther away will be more freshwater than anything else. Because puffers are collected from the wild and aren't bred in captivity it makes sense that people report keeping the fish in different salinity's because some may be collected from the more brackish part of the river while some others may be collected from the freshwater part of the river. So if you get a fish from the brackish part of the river and try putting it in freshwater, it won't live as long as a puffer that came from the freshwater part and vise versa. But if you get a freshwater puffer and put it in freshwater and a brackish with brackish then it works. You could acclimate a brackish water puffer to freshwater and the other way round just like you acclimate a freshwater guppy to saltwater. This is just my theory on how it works and I'm not saying this is exactly how it is, but it's just the way that I think. If there are freshwater figure 8's, I need to find them

 

[GreenGo]

I agree with Nils. I'm not familiar with where they're found in the wild, but I'm going to follow this post because it's interesting. I, too, am going into a research field (conservation biology and ecology, BS) but have practically been raised (in a way, as I've never heard different) on figure eights being brackish so I never really questioned it. Sure, I've done some research, and hope to breed them as a part of my business in the future, but haven't done enough to date

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[GallonsOfFun]

I agree with Nils. I'm not familiar with where they're found in the wild, but I'm going to follow this post because it's interesting. I, too, am going into a research field (conservation biology and ecology, BS) but have practically been raised (in a way, as I've never heard different) on figure eights being brackish so I never really questioned it. Sure, I've done some research, and hope to breed them as a part of my business in the future, but haven't done enough to date

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So, from what I've gathered so far they seem to do better in brackish because the salt boosts the hardness of the water. What is really affecting them is the hardness and the salt is just a mediator of that, not the cause. I may look into keeping them in fresh with hard water, but from what I've read the best way to keep it stable is salt.

 

[Terrance]

I would bring your question to thepufferforum. It's the place where a few hardcore puffer addicts hang. There a guy on their forum who has kept F8 long-term and have helped others care for their f8 by sharing his experience. He would also have extensive knowledge about their biology.

F8 do live in freshwater in the wild but they also swim along various brackish level. That is the wild. In captivity, many hobbyists have been able to extend the lifespan of f8 much more longer by keeping them in stable, non-volatile low-end brackish levels. Any brackish tank allowing large swings in brackish levels run the risk of killing all beneficial bacteria.

IMO brackish is suggested, but you can keep them in freshwater if you don't want to extend their life.


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[gemach7]

I would bring your question to thepufferforum. It's the place where a few hardcore puffer addicts hang. There a guy on their forum who has kept F8 long-term and have helped others care for their f8 by sharing his experience. He would also have extensive knowledge about their biology.

F8 do live in freshwater in the wild but they also swim along various brackish level. That is the wild. In captivity, many hobbyists have been able to extend the lifespan of f8 much more longer by keeping them in stable, non-volatile low-end brackish levels. Any brackish tank allowing large swings in brackish levels run the risk of killing all beneficial bacteria.

IMO brackish is suggested, but you can keep them in freshwater if you don't want to extend their life.


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+1 I went searching the Internet after my post in your last thread and found what everyone else is finding. There was not much information on them in the wild. I did look up the rivers around Borneo and found some of them are quite large, the largest being navigable for 140 miles. All the major rivers had 1 more large mouths that emptied into estuaries.

As to why most hobbyists have had longer life spans in brackish water this could be a lifecycle like mono sebeas. They breed in brackish then move out to sea into full salt as they age.
Reasons for this could be the greater abundance of crustaceans in the estuaries as opposed to up river.

This is only my personal inference from the experiences I've read online for this species, geographical make up of their distribution, and knowledge of other brackish fish. Not a scientific fact and by no means want it to sound as such.



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[GreenGo]

So, from what I've gathered so far they seem to do better in brackish because the salt boosts the hardness of the water. What is really affecting them is the hardness and the salt is just a mediator of that, not the cause. I may look into keeping them in fresh with hard water, but from what I've read the best way to keep it stable is salt.

That would be a great experiment! If you really wanted to be thorough, you could keep them in both freshwater with hard water and low end brackish and keep detailed notes regarding size, behavior, and any other potentially relevant data.

However, like another post mentioned, go to thepufferforum and talk to that guy about figure 8s. Idk, but I'd love to hear the results of this kind of experiment, but just be sure to keep everything else constant: same food, temperature, amount of food, etc. It may be the aquarium ecologist coming out in me, but I'd definitely be up to doing this myself in the future! Lol, am I the only one?

Anywho, whatever you find out keep us up to date!

PS, the experiment idea was just off the top of my head and may have significant flaws as commonly happens when I get this excited about something. So, create your own experiment or build off mine, but take it more as a grain of salt rather than gospel. Thank you, and have a great day!

PPS, since I want to eventually breed these, another contributor mentioned something very valid: do these puffers breed in brackish, or are they "purely" freshwater in nature (aka the wild)? I'm definitely intrigued on your findings that it's mainly the hardness of the water that affects them... Sources???

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[Trainer_Ruby_]

Isn't it with most brackish fish that they go to freshwater to spawn? I know glass fish do and my livebearers breed more of water added is fresh or lower in Solubility compared to water in my tank.
If so maybe people see them more when they're trying to spawn


Keep calm and drum on

 

[GallonsOfFun]

That would be a great experiment! If you really wanted to be thorough, you could keep them in both freshwater with hard water and low end brackish and keep detailed notes regarding size, behavior, and any other potentially relevant data.

However, like another post mentioned, go to thepufferforum and talk to that guy about figure 8s. Idk, but I'd love to hear the results of this kind of experiment, but just be sure to keep everything else constant: same food, temperature, amount of food, etc. It may be the aquarium ecologist coming out in me, but I'd definitely be up to doing this myself in the future! Lol, am I the only one?

Anywho, whatever you find out keep us up to date!

PS, the experiment idea was just off the top of my head and may have significant flaws as commonly happens when I get this excited about something. So, create your own experiment or build off mine, but take it more as a grain of salt rather than gospel. Thank you, and have a great day!

PPS, since I want to eventually breed these, another contributor mentioned something very valid: do these puffers breed in brackish, or are they "purely" freshwater in nature (aka the wild)? I'm definitely intrigued on your findings that it's mainly the hardness of the water that affects them... Sources???

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I would love to do that, it would be a lot of fun but I just spent months getting everything ready and putting my tank together and I don't have the time or money to do that all again! Maybe at some point in the future but not just yet!