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Viewing 15 posts - 31 through 45 (of 154 total)
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  • in reply to: Lab Diet for Danios #354743


    Well that sounds like a good deal Mike.

    Zeigler’s larval diet is supposed to do a good job of replacing all other larval foods.

    I would expect this to be pretty good also.

    in reply to: Lab Diet for Danios #354741


    Wow. That’s a pretty pathetic zebrafish they have on their page. Looks like some weird barb to me.

    The feed would probably work for many fish. Probably small pellet size. It is most likely pretty good nutritionally. There is a different guy (Steve Watts) at UAB that is working on optimizing a prepared food formula food for zebrafish. It is a multi-year project that has been going on for a few years.

    This company made a prepared food for zebrafish larvae a couple of years ago that has become popular in some labs.

    These and other foods specifically for lab zebrafish are probably rather expensive compared to either for fish hobbyists or for general aquaculture (which is very cheap and good quality, but comes in 50+ pound bags with a limited shelf-life and usually a large pellet size.

    There used to be a couple of other companies making foods for lab ZF, but they stopped because they were not selling enough for it to be worthwhile for them. There is also a flake food (AquaTox maybe) made for use in tests of things like toxins. The idea being to include nothing bad in as opposed to having complete nutrition.

    This is also irradiated to kill anything that might be in it. This is done because there were cases in aquaculture of mycobacteriosis being transmitted to aquaculture fish form food made of other fish (some of which had mycobacteria). Irradiation does not mess much with the nutritional compounds in the food like autoclaving (like a pressure cooker, kills everything) or other sterilization techniques would.

    The price for lab diets is high because of the comparatively small market and the ability to charge labs a lot of money.

    I use a hobbyist .5 mm pellet (New Life Spectrum) that I get in a small bucket for my small Danionins and a 1 mm size for the larger ones. Some labs use this food.

    I also use a series of live foods (Moina, Walter worms, brine shrimp, and black worms).


    I have two thoughts on why this might be:

    1) The fish’s biology is vastly different at early stages. At least up to swim up stages, gill function is probably not important for gas transfer, as the oxygen probably goes right through the skin. Some mutant fish can even develop through these stages without blood cells.

    2) The young stages should be adapted to the situations in which they might find themselves. Eggs might be adapted to living buried in muck, where they could avoid parental predation. This might involve exposure to higher levels of nitrogenous compounds. If they could not tolerate these conditions, those eggs would not survive.


    Surprisingly to me also, recently, experiments have shown the high tolerance of young zebrafish stages to these water quality parameters.

    Not widely known outside of the lab though.


    Sounds like you are confusing adult tolerances with the embryonic, larval or prejuvenile tolerances.

    Early stages of fish have different and higher sensitivities to nitrate because their biology is different.


    Dr. Neale Monks has advised that nitrates should never be above 20 ppm for any tropical fish, and preferably lower.  He has written that all species of cichlids appear to develop problems with nitrates at 20 ppm or above long-term.  On the cichlid site, they suggest that nitrate above 20 ppm may well cause Malawi bloat.  I would assume these people are referring to NO3.

    I am betting that this statement is all about adult tolerances, not those of embryos or larvae.

    Generally I don’t like blanket statements concerning different fish species and different stages of life. There is to much variability.

    More specifically, many species have different tolerances. Adult Tilapia, for example, can tolerate ammonia levels up to 2 ppm. Zebrafish larvae have been successfully raised in 0.18 ppm free ammonia (article).

    General guidelines may provide a large safety margin for hobbyists but are probably pretty inaccurate for raising larvae and could result in a less than optimal use of your resources if you mistakenly tried to meet unnecessarily strict conditions.

    in reply to: Labyrinth Fish World Horst Linke #354678


    ichthyology = study of fish; seems an appropriate grouping, by name at least.


    I like the book review. I would like to see paper reviews for the occasional paper also.

    in reply to: Finer Resolution Plate Tectonics Movie #354416


    Thanks Matt.

    I think the ancestral cichlid was supposed to have been in Africa but some how migrated to S. America after they split.

    One theory I recell is that the freshwater river outflow (Amazon and maybe Congo) made the then narrow S. Atlantic more fresh water so it was tolerable to the freshwater cichlids.

    in reply to: Sex determination in Cyprinids (Sawbwa) #354407


    Many zebrafish sex determination molecular components have been recently. Recently, it was discovered that most lab lines of ZF have messed by sex determination mechanisms due to inadvertent selection when they were “domesticated” for lab use.Let me know if you are interested in that, but I’m guessing not.


    Even within the cyprinids there are a lot of fish, probably with a lot of differences.

    Three common husbandry factors in sex determination include (but not limited to): temperature, stress (from various causes), and social group interactions.

    Normally, some species will have all or partial sex determination based on their genetics, some will be almost all environmentally determined.

    in reply to: SNAIL INVASION!!!!!!!!!! #354364


    Digenetic trematodes (flukes with a two host life cycle) are an example of pathogen requiring a second host.

    I don’t know how common they are normally but they can come from wild caught fish and probably fish from outside fish farms.

    in reply to: SNAIL INVASION!!!!!!!!!! #354361


    Some snails can definitely serve as intermediate hosts for certain pathogens, such as some worms. Eliminating a pathogens intermediate hosts can terminate any pathogen infestation to only the animals that introduced the pathogen into the water system. The presence of an intermediate host allows a pathogen (that requires an intermediate host) to propagate and infect other animals.

    This is a big consideration for me in using snails. On the other hand they do eat excess food and other stuff nicely.

    in reply to: Riveiera Maya/Quintana roo #354242


    Underwater shots, look nice!

    Do you have a box a camera goes in or a submersible camera?

    in reply to: Tom’s Poco Pozo #354223


    Intreesting. Not something I was aware of.

    I don’t know enough chemistry to suggest why it is the compound of choice for liquid carbon.

    In histology, it makes covalent bonds most frequently to amino groups on amino acids in different proteins or different locations on the same protein. It does this much more strongly than formaldehyde because it has two COH groups separated by 3 carbons (total of 5 carbons). Formaldehyde has only one COH and only one carbon. They both will react more strongly at higher pH’s. In fixing tissue (at a high concentration) glut will immobilize proteins by making a cross-linked mass and changing the chemistry of the amino groups they react with, often making the protein insoluble. Formaldehyde will mostly make one link and act through solubility changes.

    I would expect glutaraldehyde to react with something pretty quickly in a mature aquarium. It may also react with ammonia floating around in the water.

    I have no idea how this might get the carbon into plants. Perhaps bacterial degradation of the modified proteins.

    Denitrifying filters (filters that use bacteria to remove nitrates by turning them into nitrogen gas (or other things)) use a carbon source (often carbs or alcohol) that is fed to the bacteria in a oxygen depleted filter space. The bacteria use the carbon from the carbon source and the oxygen from the mitrates.

    in reply to: Tom’s Poco Pozo #354221


    I have also just started dosing home-made liquid carbon (gluteraldehyde solution) as a bit of an experiment as I;ve never used it before and it’s very cheap.

    Whats the logic behind using gluteraldehyde?

    I would assume there are a lot of alternative chemicals that could be used as a carbon source (like alcohol).

    My familiarity with gluteraldehyde comes from doing histology where it is a very strong fixative (cross linking protein and other chemicals via amino groups). Its kind of toxic. As is formaldehyde which is used to treat some external pathogens.

    in reply to: Jenynsia lineata #354060


    I have read similar things about the four eyed fish (Anableps), which I also heard somewhere was disproved.

    As I recall, the two genera are fairly closely related.

    Too bad the handedness can breed with each other. If the handedness was genetically determined, I was hoping for two separate breeding populations in the same area, or perhaps an alternation of generations between breeding with one handedness and the other.

    in reply to: Rhinogobius flumineus ‘wolf goby’ #354010


    Unfortunately, I’m getting very different growth on different fry… I have some that are 12mm now, with huge extensible stomachs, and naturally very fat already … and some skinny 8mm .. I know they are eating and surviving, but I also see their bellies are tiny. Wonder why….

    I find this interesting Mike.

    It would be interesting to see some pictures of the big and skinny ones.

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