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Thread: oxygenised bait

  1. #1

    oxygenised bait

    Its a new year and I haven't asked any dumb questions yet, so here goes.

    Anybody used a bait oxygenising system like this one?

    All the stuff I am reading about injecting O2 into bait tanks seems believable. They reckon it really gives the livies a supercharged kick and from my experience changing livies to fresh ones with a bit more wiggle in them often turns on the predators. The other big seller is that when you first catch livies they are freaking out and use more oxygen than some normal systems can put in. I would imagine this may even help the survival rate of even finnicky herring.

    What's the consensus? Is it just a rich boys luxury toy?

    Oh yeah, I am also aware oxygen is a flammable gas so be warned Mr Safety Concious, I will fly down your throat if you mention how dangerous having compressed oxygen on a boat at sea would be! Ok!!!!? These units ship with marine grade brass regulators for this very reason. Apparently in the US it is illegal to sell standard hospital grade oxygen units for the intention of use at sea.


  2. #2
    Hi Mooks,

    Oxygen is not a flamable gas, but rather, it supports combustion. If you want something to realy burn, introduce oxygen. This is seen when the wind blows and "fans" the fire. The fire is enhanced by the extra oxygen carried to the flame, in the wind.

    In theory, oxygen may assist the livies, but I doubt it, due to the capicity of the water to carry a given amount of oxygen at atmospheric pressure. Let me explain in very simple terms.

    The volume of oxygen that air or water can carry is dependant on a complex law of pressures, and involves Dalton's, Boyle's, Charle's and Henry's Laws ... to name a few. In simple terms, the only way to increase the oxygen carrying capicity of water, is to place it under pressure in a given space.

    Grab a bottle of soft drink, or beer, from the fridge. Now, crack the top off. Hear the hiss? That's the pressure escaping the container, and the liquid. That gas was only disolved in the liquid due to the pressure placed upon it. The gas level is now on the decrease and will level out to the natural capacity of that liquid to carry that gas in no time at all ... e.g. flat drink.

    That explains why oxygen would be a complete waste of money. The use of an air pump, or a water pump, will do the job. You siimply need to move the water around so gas exchange takes place more rapidly at the surface, where it normally takes place. Of course the same process takes place in the atmosphere, and inside living organisms.

    Enjoy your beer .... if it hasn't gone flat.

  3. #3
    Wouldn't it be dangerous having oxygen on a boat at sea ???

  4. #4
    Dear Gunna, piss off, love Mark!!

    Dear CQ_Freshie,

    Thanks for the explanation. Contrary to popular belief though I am actually a bit clever myself and know most of that. The bit about oxygen being a flammable gas may have been technically incorrect but as you would be carrying a bottle of compressed oxygen next to a container of fuel and possibly oil and other nasties I said this to stop people giving me the safety lecture. I was just trying to save a few words.

    Regarding the oxygenisation. If you read the site they are getting pretty techo here and measuring dissolved O2 in PPM. They say that you cannot super saturate seawater with oxygen using any standard live well system that pumps in fresh water or uses an aerator. They then show a diagram of a meter measuring DO (dissolved oxygen) with a standard livewell system and then their system.

    Read the link here and get back to me it's quite interesting.

  5. #5

    Re: oxygenised bait

    Quote Originally Posted by gunna View Post
    Wouldn't it be dangerous having oxygen on a boat at sea ???
    lol, you're a sh!t-stirrer!
    Fishing for the thrill, not for the kill

  6. #6

    Re: oxygenised bait

    I think what you have to work out is
    will increasing the water's oxygen level automatically increase the oxygen levels of the fish's blood. If it will, I'm sure it'd help to some extent.
    But just how much is the big question.

    I used to have to inhale oxygen for a neurological problem, and was always working out my blood/oxygen levels, because oxygen (hospital grade ) isn't cheap by any measure. And there's a point that isn't that high, where you're really into overkill. You're blood can only carry "so" much oxygen (and I can't recall exactly how much), so introducing it at higher levels is just as good as pouring it out the window.

    When I was into breeding aquarium fish I discovered placing fish in plastic bags to tyransport gives around an hour or two before things get desperate, but when packed using compressed oxy, instead of the environmental levels of atmosphere, they can be placed on planes and sent interstate etc..4, 5, 6 hours..

    But there's more to that than at first observation too. Like of course we're dealing with closed environments, where the amount of oxygen the fish have is completely limited to what's int he bag.
    But f there's an areator going that's another thing. And that's the point I'm really wondering about, and I think is the point that will make it work or fail.

    What I mean is when I first started keeping fish, I thought the air bubbles the air pump was putting into the tank was the oxygen the fish breathed. I suppose everyone knows better than I, but it came as a surpise to me to find this isn't the case.
    The air pump makes a stream of bubbles so that a current is made in the tank, making all the water move around and contact the surface, and also so that the surface tension is broken.
    Gases excahnge freely through water, so long as the surface tension is constantly disturbed. And so long as all the water in the tank is circulating constantly, and comming in disturbed contact with the atmosphere; oxygen exchages with no other mechanism.
    So from what I understand of fish, water and oxygen (which is all very limited ), the best way to increase the oxygen levels of a tank is to increase the amount of movement in the tank. It's critical that the surface is constantly moving, hence greater amounts of air flowing through the air pump, making a greater disturbance at the surface point is what increases the oxygen levels, not, as mentioned, the actual amount of air pumped in per sae.

    I imagine pumping straight oxygen into the water would simply see it rise to the surface, dissipate into the atmosphere and it'll be lost to the sky. If the tank is somewhat sealed, the air above the water of course will increase in oxygen levels, but just how much you can increase the natural exchange rate of these gasses is the point you have to find out. I mean the exchage is only taking place along that thin line where air meets water, and the question to me seems to be "will simply making more oxygen available at that point automatically mean the water will obsorb it?" If it will, I'm sure the fish will get it into them, but will it be a notable difference will only be a matter of expereince I think. I reckon all the conjecture in the world will only be sorted out by seeing what happens. I mean in a truely practicle sense.

    I know fish keepers are a fanatic lot, and with electricity bills in the thousands, filters that cost the same, and endless other high costs, I myself have never met anyone who has attempted to increase the oxygen levels of their tanks with compressed gas. I have met people that pump co2 into the tank for the plants, but that's abit dif. In fact, air pumps are not the most popular method of increasing oxygen either. Simply increasing a greater amount of action at the surface is what people do, and they use spray bars as a rule to do this.
    just like the oxygen levels in a stream are higher in the rapids than in the deep, and significatnly higher than deep down in deep water. the reason isn't to do with anything being pumped in, simply that the water is being aggetated and oxygen is exchanging more in the rapids.

    Of course I wouldn't have a clue if what the system propose will actually do anything, but I'm sure the way from here for you to find out, is to understand just how much more oxygen can be disolved into the water, by simply increasing the amount of oxygen ABOVE the water line of the tank, because I'm quiet sure that's where it'll all end up. Perhaps heaps of oxygen, and heaps of water movement? but the issue really has to be just how to get that oxy in the water chemistry. I'm just wondering if the water is aggetated to it's max prac. level, is the oxygen exchange happening at it's peak, regardless of if we sit more oxygen ontop of the water?
    That's why I m,eantioned my expereince with oxygen in my home. My lungs can only convert "so " much oxygen into my blood. Increasing the amount of oxygen into my lungs beyoing what can be converted is watsfull. So the critical point isn't "how much oxygen is going in", rather, "at what rate can we make the water accpet the oxygen greater than natural?" Or so it seems to me.
    But one thing for certain, if the tank isn't somewhat sealed, it really has no chance of improving anything in my mind. Because it has to be at water surface level to "exchange", and so it has to be kept there somehow, while working on how to increase the water's ablity to recieve it.

    I hope I haven't just gone over what's plainly obvious, as I said it was kinda educational to me to discover these things. It wasn't that long ago I thought pumping air into water was what made oxyen available to fish.

    I don't keep live baits at all, but if I were to, I reckon personally I'd just make sure as much fresh sea water passes through the system as possible. I wouldn't even use an areator, so long as I could manage a flow system which didn't stop replacing the water quickly. That movement alone will agetate the tank enough to see a propper exchange of oxygen.
    But that's just my thoughts on it.

    Last edited by robyoung2; 04-02-2007 at 01:19 AM.

  7. #7

    Re: oxygenised bait

    Very interesting Rob,

    I may give these yanks an email and see what they think about the sealed tank thing. I was aware that most of the oxygen exchange was at the water level but thought that pumping 100% O2 in as bubbles would contribute as well on the way up.

    We'll see what they say.


  8. #8

    Re: oxygenised bait

    I wonder if asking aperson that is as much an expert as possible in fish keeping/breeding mightn't get a more informative answer. I noticed someone on these boards asking about the health of a pet barramundi. In the replies a member answered the question, he works a job breeding barra. Of course when the water gets hotter, the oxygen levels decrease, and in the middle of summer, people can loose some pretty bloody expensive fish real quick. I imagine people that breed thousands of dollars worth of barra woud be right up to speed on how to increase oxygen levels, and what you're looking to find out in general.

    I didn't mean sealed tight BTW, but then I'm sure you get what I mean.
    I've been thinking about it heaps since I read this last night, and I reckon it would help over-all, So long as the oxygen could be kept close to the top I mean. It's an interesting question hey.
    let us know what you discover won't you.


    PS. Years ago someone told me Barry Pollock used a small dose of anti-biotics in the water to keep his yabbies healthy. They claimed he dropped a bit in every time he refreshed the water, supposedly stopping any infections from injury while being pumped, etc..It was said that 3 in the morning at the 'pin, you could almsot hear a hook crunching it's way through the shell they were so fresh.
    I tried it and killed a whole night's worth of bait lol. Great idea but. Maybe I just used too much? I recall the docotr lookin at me like I'd lost my mind when I asked him to prescribe the stuff.

    Last edited by robyoung2; 04-02-2007 at 08:59 PM.

  9. #9

    Re: oxygenised bait

    Yeah Rob, that was the point of my response. As a professional in the emergency medical field, I do have a knowledge of gas percentages and cascade. It is, however, difficult to explain in simple terms.

    The volume of disolved gas in any fluid is directly proportional to the temperature of that fluid and the pressure exerted upon it (previous example given as that pressure being in a sealed container.... as in that carbonated drink, or in the plastic bag used for fish transport).

    Now, if one uses a difuser (air stone, tube with holes in it, etc) to introduce oxygen into the water, the amount of oxygen absorbed at the surface of each bubble is miniscule. Most oxygenation or rather, gas exchange will take place at the surface of the water where it contacts the oxygen enriched atmosphere. As stated, this is directy proportional to the pressure.

    I would suggest that the livies would benefit, not from oxygen being used, but rather from enhanced gas exchange at the water surface. That is, excess carbon dioxide and other gases leaving the water at the surface, and oxygen entering the water. That is assuming all else is well with the water ... temperature, salt content and other impurities etc.

    Oxygen pumped into the live tank will work to a degree ... if the tank was sealed, and the pressure maintained low enough so as not to harm the fish, but I don't believe the expense will be of value. Just use a water pump to constantly replenish the water.


  10. #10

    Re: oxygenised bait

    also a large flatter tank (with more surface area) will keep fish much better than a deep but skinny one (with the same amount of water) because as explained, oxygen exchange take place at the surface, never had a dram with live bait in a well designed tank. tuna tubes and things work as well, but not all that flash, in my experience that is.

  11. #11

    Re: oxygenised bait

    just tp prove that theory, when on holidays down tha coast, we used to keep yackas alive over night in a little inflatable plastic pool (because of the big surface area), then in the morning, we just filled the bait tank from buckets from the day before, scooped up our live bait, launch the boat and have a tank full of livies without mucking around early in the morning catching them.

  12. #12

    Re: oxygenised bait

    cq Freshie, I'm really sorry mate; I didn't read your reply, which is unusal for me; I usually read a thread right through when I reply (like everyone I suppose). I've just repeated you, I didn't mean to.

    It's interesting what you thought of with pressuring the tank, in the same way as carbonating a drink in reverse (I mean co2, rather than oxygen). I was only thinking in terms of enough sealing to stop it completely escaping, so it was constanly available to the water line.

    I believe a similar discussion to this rages with drenching plants with co2. Under controlled scientific experiment, it's considered possible to increase plant growths as high as 5 times! So I've read at least. But while it's unquestionably benifiical to realease co2 around plants, it's far more complicated than is possible without a lot of equipment; and so in praticle terms people realise far more modest realities than advertised.

    In fact it's far easier to increase plant growth with C02 than it ever would be to increase water levels of 02; but I'm sure you get what I mean. There's people around espousing some great theories, all which usually financially benifit those promoting it. Not saying it's all crap either.

    Last edited by robyoung2; 05-02-2007 at 11:30 AM.

  13. #13

    Re: oxygenised bait

    The site I have put up there mentions some really interesting about keeping bait alive but the thing that got my attention is when you start reading what the US guys that are into fish breeding and transportation say. They virtually all use O2. There's bloody reams of info on that site. I haven't bothered looking at any others yet as I am still slowly churning through that one.

    The other thing I am interested in is the mortality rate of finnicky bait like herring. According to the yanks the stress put on them when they are initially caught makes their oxygen demand go through the roof so if you super saturate with oxygen they have it there when they need it most. I know my pulse/respiration rate would go up a bit if a huge giant dude yanked me out of the ocean with a net!

    I have kept yakkas alive overnight for land based sessions down at JB in my day and they were no worries. They'd survive in a warm bucket of yellow liquid as they say.

    I think the exchange rate of oxygen from water to a fishes blood through their gills may not be fair to compare to a human breathing gas into lungs either. But I'm no expert.

    Of course a good live tank with circulating water does the trick for most of us at sea in big flash boats but if you have ever had an entire tank of herring go belly up after a few minutes when you are land based after jacks it makes ya scream.

    Tis interesting though. I'll pop off an email to the yanks in a minute or so. We know they don't mind talking!

  14. #14

    Re: oxygenised bait

    Some of us yanks add the aquarium product Ammo-Lock to the water the bait is kept in. The accumulation of ammonia is what kills live bait quickly. Ammo-Lock neutralizes the ammonia the bait release as waste and during respiration, especially under stressful conditions. Ammo-Lock works great for keeping all kinds of baits that normally die in an hour or so alive in your bucket all day long. Seems to work just fine for anything that breathes underwater. You should be able to get it fairly cheap at any aquarium store. Just follow the directions and you will be surprised at how long your bait will stay alive and perky. One teaspoon treats about 10 gallons. The addition of a small aerator as well would be ideal but you won't need need one for the most part if you use Ammo-Lock. If you have a larger live well you may need to look for larger size Ammo-Lock in the fish pond section.

    Last edited by bordeaaj; 09-02-2007 at 01:41 PM.

  15. #15

    Re: oxygenised bait

    hey bordeaaj,
    that ammo lock looks intersting. themooks, I think this comes down to how much you want a new toy.



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