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FAQs on Aquatic Metabolism

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Salmon Question... anadromous adaptation  12/7/08 Hello, <Andy.> I have a question about salmon and seeing as Google doesn't appear to want to help me I thought that perhaps you may have the answer. I learned long ago that taking fresh water fish and putting them in salt water is a bad idea. <Some fish can make this journey, but not in an instant!> Likewise, taking salt water fish and putting them in fresh water is also a bad idea. How is it then that salmon can go from fresh water to salt water and then back again without shriveling up or exploding? What's different about them? <Freshwater fish drink little water and produce a very diluted urine, while saltwater fish drink more water and produce a concentrated urine. Fish can also use their gills to adsorb salts in the case of FW and secret salts in  SW. Salmon have the ability to adapt this over a period of time. When they come down river towards the ocean they undergo a change called smoltification (a search of this term will give you your answers too). In that time they will adapt to the marine environment. On the return to FW to spawn, they will spend some time at the mouth of the rive adapting. Even with their ability to go from fresh to salt, an instant osmotic shock will kill them.> thanks. ~Andy <Welcome, Scott V.>

Very Coldwater Fish - 3/5/08 http://news.bbc.co.uk/2/hi/science/nature/7279444.stm <Brrrrr! Have to shut down behaviorally due to enzyme energy matters... Come on global warming! B>

I know certain fish can transition from freshwater, brackish, and saltwater.    5/11/07 Hello Crew, I hope everyone is having a good day. <So far, so good!> I know certain fish can transition from freshwater, brackish, and saltwater. <Indeed. Such fish are called "euryhaline fish" as opposed to "stenohaline fish" that are confined to freshwater or saltwater habitats their entire lives.> Does their food need to change also? <A good question. It depends upon on the fish. Certain fish live in one environment for part of their life cycle, and another environment the next part of the life cycle. In many cases, there are dietary changes along with these ecological changes. Atlantic Salmon for example live in freshwater as hatchlings and for the first few months of their life, feeding mostly on insect larvae. They then go to sea for a few years where they feed on crustaceans of various kinds and small fish. Once they reach a certain size they will migrate back into rivers to spawn, but during this spawning run they don't feed much, if at all. They then return to the sea and begin feeding again, in preparation for the spawning run the next year. Other fishes, like scats, simply eat whatever they find wherever they go. These fish move between freshwater and the sea all the time, and what they eat depends only on what they encounter. For the aquarist, one of the striking things about brackish water fish is their greediness. The problem is making sure you don't overfeed them and compromise water quality as a result. Some brackish water fish are predators, and need a primarily meaty diet, but most are omnivores and take a variety of foods including algae, plant matter, frozen foods, and pellets.> I know the salt levels change, but what other effects does it have on their bodies? <The change in salinity is the main thing euryhaline fish have to deal. So in freshwater a scat (for example) will be pumping out excess water while conserving salt, but doing the reverse when it is in the sea. Secondary issues will be differences in temperature (the sea varies more slowly than neighbouring rivers so may be cooler or warmer depending on the season), pH, hardness, and other aspects of water chemistry. Salt water also provides more buoyancy than freshwater, and euryhaline fish also need to adjust the amount of gas in the swim bladder to keep the same level of poise when swimming.> I am particularly interested in mollies. <The relationship between mollies and brackish water is complex. Mollies are naturally found in freshwater, brackish, and marine environments. But in aquaria they tend to do poorly in freshwater, being very prone to fungus, finrot, and the "shimmies". It is not 100% clear to me that they need brackish water, and some aquarists have suggested that it is the ambient level of nitrates that matter. In brackish water nitrate is less toxic than in freshwater, so the mollies will thrive even if the nitrate levels are quite high. It certainly seems to be the case that people who have luck keeping mollies in freshwater aquaria also keep the nitrates at very low (practically zero) levels. In ordinary community tanks where the nitrates are around 20-100 mg/l, mollies just don't do well.> Thank you,      Ann <Cheers, Neale>

Fish life spans  - 04/24/2006 Hi Bob, Thanks for your reply - I'll look at the website later - I'm currently browsing the reefs.org site mentioned in the back of your book. <Also very worthwhile> If I could just ask one question - why is there so little information on expected life-spans of different species anywhere? <Such data has been compiled for a few species... by public aquariums... and can be calculated for many more by some perusing, math with data presented on fishbase.org> Best regards. Martin <Bob Fenner> Ultrafluorescent  9/7/05 Hi friends: We live in Baja Sur, Mexico... so far on the ocean at night, and not always there are special things that shines very brightly, specially related with the movement...nobody here knows the name of this parasites, fish, who knows.... They are supposed to shine more on bays, near the rocks or at the shore, but even if you inside the ocean they are by tons, they leave like a wave of glitter....so nice, so peaceful... By any chance, do you know the name of these things? We would appreciate your help Regards Hugo and Josefina <There are many phosphorescent organisms in the sea... some are indeed spectacular... the most common in Baja are largely algae that "sparkle" when disturbed by surface activity. Bob Fenner> Fish Osmosis Hello, this is Ahra Lee. I'm 9th grade and I have biology Essay. My question is why the freshwater creatures should not drink seawater and how can I use the terms osmosis and diffusion in my explanation? Please e-mail me back, thank you so much and I'm sorry to take your time. < Your answer comes from a book titled "Aquariology The Science of Fish Health Management" By Dr. John B. Gratzek: Diffusion is the movement of molecules from a higher concentration to a lower concentration. Osmosis is the diffusion of molecules through a semi permeable membrane. In freshwater fishes, the concentration of dissolved salts in the blood is greater than the concentration in water. This makes the osmotic pressure of the fishes blood greater; water diffuses through the gill membrane into the blood and the salt ions diffuse into the water. The kidneys of the fish put out lots of urine , mostly water to maintain the proper salt concentrations. If saltwater was ingested by a freshwater fish its kidney's and gills would probably not be able to excrete the excessive salt concentrations to maintain the correct salt balance and suffer kidney damage.-Chuck>

Algae Queries For my sixth year Advanced Biology higher project I have decided to do  Algae growth and the factors effecting it's growth. I realize I will have to  grow it in the laboratory and then will immobilize it into jelly beads, using a   solution to measure the uptake of carbon dioxide. I would be grateful for any   advice on a better experiment or any changes I can make to mine to add to the   reliability of results etc. (keeping in mind it is a school experiment, so   nothing too advanced or complicated.) thank you very much, I would be really   pleased if you could get back to me with some feedback, Susannah Bennett >>>Hello Susannah, At the most basic level, algae needs light and a nitrogen source, (nutrients) and or a phosphate source to grow. So, you could vary the amount of nutrients and light in different cultures. One has no light, but high nutrients, one has tons of light, but no nutrients, one with high light and high nutrients, med light and high nutrients, etc, etc, on and on. :) Same with phosphates depending on how complicated you want to make this. You can measure the nutrients in the water, and phosphates with test kits.   I would use a macro algae such as Caulerpa, and simply weigh it, rather than messing with solutions and jelly beads, but that's just me. :)Seems like that is needlessly complicating things. Regards Jim<<<

Re: articles Good after Madam! I am Catherine Chan of the university of the Philippines, third year, and presently preparing for my thesis. I'm interested on ichthyotoxicity. Because of this I would like to ask help from you. I would like to ask a copy/ies of any published articles related to my thesis so they will serve as my references and guide as well. I hope you understand. I'm hoping for your kind and immediate response. mailing address: University of the Philippines in the Visayas Cebu College Gorordo Ave., Lahug Cebu City 6000 <Have no writings specifically on the topic. You're welcome to cite what we have re family references posted on WetWebMedia.com. There is a search tool (Google) on the homepage you might use with the terms "toxic", "ciguatera"... Bob Fenner>

Re: do fish sleep? Hey Bob, <Howdy> I am a 13 year old student . I would like to know if fish sleep. I would like to also know if you know any facts that might interest my age group about sleeping fish. <Fishes do have "down periods", with many reef species actually laying about on the bottom during the night (or day), and pelagic (open ocean) species going into "sleep mode" at night. Some interesting behavior you might look into is the practice of nighttime cocoon-making of some species of Parrotfishes. Please see here: http://www.wetwebmedia.com/parrotfi.htm Bob Fenner> Thank You For Your Response.  Chris Hulsey

Bio question Hi there I am a biology teacher, and I came across your web page while trying to search for interesting demonstrations to use in a senior biology class. If one puts insulin in the water of goldfish bowl, will the goldfish react by slowing down? Will it be an obvious effect? <Hmm, don't think the goldfish will take in appreciable amounts of insulin in this fashion. Freshwater fishes don't "drink" much of their environment, or "soak it up"...> Can you suggest other quick biology demonstrations? <Many! I was you... a H.S. life and physical science teacher... What do you have in mind? Bob Fenner, just back from Fiji> Thank you Dan Singleton

Iodide/ine, lower vertebrate endocrinology... ROBERT I do not have the CASCO system. I have the Trident system here. I don't have the same issues they have about their water quality, per se. The iodide I am treating with is the Kent Tech I. I add 1200 ml per week as per instruction on the bottle since I have a 6000 gal system. <Wowzah!> How does the macro algae work?  <Do you mean "how" as in how to set-up, or actual insights as to its function? Both are touched on in various places on our site (WetWebMedia.com)... maybe use the Google Search tool there> I might want to set one up in my sump area. I plan on having my pipes camera'd since they cannot handle a high water load down them without burping and causing supersat. <Hmm> I am seeing increased algae growth, as was expected, with the iodide treatment. I add 200ml once a day for 6 days for the next week and a half and then we half dose it and then just supplement.  <Do you actually see/record a residual a day later? Is there any "standing" concentration?> I have a case of goiter that I think is about to die, since she is breathing awfully heavy like the other cases did. Goiter is increased thyroid production due to a blockage in the uptake of iodide.  <Hmm... more like a lack of T4 et al. hormones due to a lack iodide...> It creates tumors usually near the ventral side of the gills causing impediment in breathing. I was told by other large aquaria that that has helped in their system and even reversed those that were symptomatic. <Interesting... my Master's work/thesis involved lower vert. endocrinology: Hormonal manipulation of Mullets...> If they have internal parasites, is there anything I can put in the food to get rid of something like tapeworm?  <Mmm, yes... there are not-so specific anthelminthics, vermifuges... I would not use these without maybe sacrificing, cutting up and searching some otherwise lost fish livestock first.> They eat like hogs, so that would be the easiest means of treatment. Let me know. Thanks ,deb., <We can, maybe should chat a few issues over first. Am back "in town" for a while now, sorry re delay of response. Bob Fenner>

Fish metabolism Hi, <Hello> I am hoping you can maybe answer a question for me that no one else seems to know. I have a Copperband Butterfly that I got a week ago. I bought it knowing it was not eating yet but had just come into the store. <Quite a risk> I also was aware of problems with these guys not eating in captivity, however, after some careful consideration, decided my 1,000+aiptasia had to go and I was at my last resort. <Yikes...> I didn't see the fish really eat anything for the first few days, but then I saw it "poop". Do you know how long it would take for the fish to eat and have it come out? <Hours to a day maybe> That made me realize that if it is less than 24 hours, he was eating something... <If more than a day> Now-he seems to pick bloodworms off of rocks here and there and possibly Mysis, so I think he might be OK. Of course, now he's in a tank of his own but will be in my large reef tank as soon as I know he eats and is disease free. <I would dip this specimen and place it probably... worth the chance of moving infectious, parasitic agents> Anyhow, just wondering if you know anything about fish metabolism. <Had a couple of college courses in this topic related fields. Bob Fenner>

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