figure eights in freshwater? with plecs?

[pigboy]

Hi everyone - I keep 2 figure 8s myself in low brackish water 1.005 sg - 1.007 sg dependent on water changes. I always make my salt water from de-ionized tapwater with marine salt added. Before discovering the puffer forum I used Dr Klaus Ebert's book as my reference to puffer care ( ISBN 393170260x ) to quote the good Dr
' Unfortunately if kept long-term in fresh water this species tends to be delicate and disease prone. By contrast tetreodon biocellatus has proved hardy and resilient in brackish and marine aquaria. '

[Myaj]

Wow, exactly.. I always get nervous when people suggest straight RO water, that is a nightmare crash of a tank waiting to happen!

And Norway Reef, don't forget, we all have different tapwater. For some people its super soft, some is right in the middle, others have liquid rock that reads on all levels right there with brackish, other than the salt content.

And I'm still not comfortable with the "fish in the wild" statements. AFAIK, no one has ever tagged juvenile, wild puffers and followed them around for 10 years or so to see how long they live in the wild. So I really have a hard time believing anyone has an accurate "wild life span". Fish kept in home tanks should definately live longer lives than they would in the wild.. they have no predation to face, a steady supply of food and, if its a good fishkeeper, clean water and no exposure to pollutants, diseases and parasites.

[Boxermom]

And I'm still not comfortable with the "fish in the wild" statements. AFAIK, no one has ever tagged juvenile, wild puffers and followed them around for 10 years or so to see how long they live in the wild. So I really have a hard time believing anyone has an accurate "wild life span".

Can you cut them in half and count the rings?

[RTR]

I would love to hear of some newer long-term captive trials on any puffers, including F-8s. For me they are clearly best kept in light BW, but others may well get differing results. The wild info is always interesting, but as already stated, is not particularly germane to long-term captive housing - the situations do not compare, and the risks are completely different. It should be noted that my trials were all of solitary specimens (the simplest case, and IMHO the best for most puffers).

I may well be responsible/guilty of the idea that alkalinity may be as or more important than the salinity. I have discussed this on this and other boards, but did not generate enough data to prove it during the original trials. Those fish in FW (my tap, GH ~9, KH 7-8) with RFUG aragonite substrate did better than those with inert substrate (small gravel), but the numbers were too small to be certain of significance. As the light BW was clearly "better" for lifespan and health, I had no justification for starting another 15-20 year study to pin down an interesting sidelight, or to determine if was alkalinity, Ca++/Mg++, or just TDS/osmolarity alone.

[Pufferpunk]

And SG is much easier to regulate than hardness.

RTR, still waiting for that great article on your F8 study!

[Fella]

Fish in aquariums SHOULD exceed average wild life expectancy. No competition.
If they do better in brackish(which you admitted), then how can you say that they are freshwater period. Just because YOU have never studied one in brackish water doesn't mean they are freshwater.

Not entirely true. While some captive freshwater and fish do exceed their natural lifespan the vast majority do not, no matter how ideal the aquarium is.

I said they do better in brackish water over freshwater tap, however, RO/DI freshwater is better than slightly brackish water from my findings.

In the wild these fish are freshwater, period. No scientific documentation will tell you otherwise.


Do you mind giving us the exact numbers for reference? I'm not doubting you, just curious.
Seems to be about 13 years, not 18 years as some people may tell you. I have kept mine for 13 years and they were about 2 years old when I got them (very accurate estimate).

This is all very interesting, I've always suspected that keeping them in hard, alkaline fresh might be equivalent to brackish (as can be done with other fish).

How come you got to study figure 8s? Do you know anything of their breeding behaviour?

[pigboy]

Dear Mr Norway,
I know this is a constant source of debate between Tetraodon enthusiasts, the fresh/brackish figure 8 thing : surely eventually you need to go back to source - Ebert may be wrong but he knows more about puffers than most, having studied them for over 40 years. I have always found the Aqualog books useful as a fishkeeper, but I am open minded - if you truly believe figure 8s do better in freshwater than brackish I want to know because I want Fatty & finny to have a good life.

[kjharve]

NorwayReef has been rather quiet lately!

[Myaj]

I hope he doesn't think we are ganging up on him.. its just that we want the best for the fish and if someone has a theory or experience that proves better than we know, we want to hear it!

But there's a big difference between proof and speculation, and I'll take many years of proof over a few months of speculation anytime.

[manutius]

But there's a big difference between proof and speculation, and I'll take many years of proof over a few months of speculation anytime.

Thats a great point and I agreee with it wholly. If the sceintific study and report can be made availabale to us then we can asses the info given. If the info is based on a hunch though, its not fair to pu that info on the board.
Please don't feel that you are being ganged up on, it is the same for anyone that challenges the way things are done or beleifs that are held. Just look at that dude who tried to prove the earth went around the sun

[puffer_puff]

The dude that tried to prove the Earth travels around the sun was "Copernicas," from whom we get terms such as "Copernican revolution," though there may have been others.

On the topic of someone in this thread claiming to keep fish for a long period of time in RO/DI water, I do not believe he was claiming this. It may have been a mixture of RO water and tap water, which would naturally lower the GH while keeping other parameters at acceptable levels.

[RTR]

Personally, I would love to see data on long-term captive maintnance of any fish in RODI - with TDS figures. But I would never subject hard water or BW fish to such treatment myself. Without hard data (meaning readings and graphs of the TDS over extended time) comments on the subjective conclusions are worth just about as much as the original statement - basically nothing.

Set a tank w/RODI using inert substrate and just top it up rather than large percentage changes routinely and it is not going to stay at RODI levels long at all. The TDS will climb steadily and can equal any OTS tank in months. Defining a water condition by the original setup or the makeup water alone give little or no info on the tank profile without supporting data. Take all such comments with a large grain of salt.

[coldmachineUK]

Also doesn't RO/DI water remove all the minerals which may be beneficial to the fish/tank?

I've read so much on the debate between FW and brackish for F8 puffers and I think what dinsdale says is spot on: they probably live in varied salinities in the wild from FW to higher than the recommended aquarium S.G. of 1.005. They move about. It's the same with species of gobies. I think it's known as amphidromy, and can be dictated by age, mating behaviour and so on. To replicate varied salinities indoors would be very difficult, so that's where the 1.005 middle ground comes in.

[Pufferpunk]

Also doesn't RO/DI water remove all the minerals which may be beneficial to the fish/tank?

Exactly

[nmonks]

What disturbs me about this thread is that we have aquarists telling people who have seen fish in the wild that what they have observed is wrong. This is the kind of attitude that doesn't endear people to specialist forums and scares newbies right off.

Poor old RTR and his 18 year old fig-8 pufferfish gets dragged out every time this debate is discussed, and while his experiences certainly have value, they aren't Gospel and shouldn't be treated as such. The normal lifespan of this species is obviously far less than 18 years, just as the guy in China who lived to 120 isn't an indication of a normal lifespan for human beings. There's genetic variability and a whole bunch of environmental factors at work.

Without a _controlled_ experiment putting large numbers of T. biocellatus from a _single population_ into a bunch of freshwater and brackish water tanks each exposed to _identical maintenance regimes and diets_, we will never know for sure whether brackish water trumps freshwater.

All the scientists studying and collecting them seem to be saying these fish live in freshwater. I haven't read a single scientific paper that mentions them coming from brackish water (just as I've never seen one saying T. fluviatilis lives in the sea!).

There could be a myriad of other factors at work. Salt reduces the toxicity of nitrate. Nitrate seems to be harmful to puffers. Ergo, T. biocellatus in aquaria with 40 mg/l nitrate will be less poisoned in a brackish water tank than a freshwater one. This is almost certainly the case with mollies: freshwater fish in the wild, brackish water fish in aquaria. Kept in high-nitrate freshwater tanks they are plagued with diseases, kept in brackish or salt water tanks and you can use them to cycle new aquaria without them so much as blinking!

Salt may also be providing some trace element lacking otherwise. Bichirs, for example, won't spawn until you add seawater, but they are 100% freshwater fish in the wild. They seem to need the potassium iodide, because if that is added on its own, they will spawn as well.

So, can we please be nice to the new guy, and listen to what people say instead of jumping on top of them for not toeing the Party Line?

Cheers, Neale