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BillT

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Viewing 15 posts - 1 through 15 (of 154 total)
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  • BillT
    Participant

    Turns out that this article is in a whole issue of this journal (Zebrafish) that is on zebrafish health issues and it is all now open access, so you should be able to get at any of the articles.

    It can be found here: whole issue link.

    in reply to: Happy Birthday Matt! #355383

    BillT
    Participant

    I second that. Happy Birthday Matt!


    BillT
    Participant

    Nice find!


    BillT
    Participant

    Found a pdf button there also. Works better.


    BillT
    Participant

    Great find Stefan!

    I was able to print out a pdf (print and then save as a pdf) here

    in reply to: Rain water problem… #355360

    BillT
    Participant

    I have used larval zebrafish (1-5 days old) for bioassays (in a lab where there are thousands available). Any reasonably sized fish you are not too worried about losing could work for this purpose. Medaka and fathead minnows are used a lot for bioassays also.  Daphnia are a classic critter for bioassays. They also breed frequently so all developmental stages might be present.

    Molluscs are reputed to be sensitive to copper/zinc which is why I suggested them.

     

    Conceptually a bioassay is pretty simple. A negative control could be helpful of you do find some positive results to your assay (to rule out something like contamination from something other than the test water, but it doesn’t seem you need it.

     

    Other than what you are doing all I could suggest is to give them more time or try some snail eggs (maybe they will lay some). Embryos are often more sensitive and might respond at lower levels of contamination.

    in reply to: Cycling my 29 gallon #355354

    BillT
    Participant

    If your water is very soft, you might want to add some carbonate buffering.

    7 carbonate molecules are used for each ammonia molecule processed by your filter.

    in reply to: Rain water problem… #355350

    BillT
    Participant

    I don’t know much about washing that stuff off but, it sounds like you may be keeping your fish in soft water. If so, this makes your problem more difficult since copper and zinc toxicity goes up in soft water and is reduced in hard water.

    If you can get hold of some of the material (or perhaps look up its chemical properties) you could see what might dissolve it before trying to do the whole roof.

     

    From my experience running a research zebrafish facility, I know zinc and copper can have adverse effects on zebrafish down to fractions of a part per billion concentrations (both chemicals present at the same time, so might not be so bad in your case) in soft water (below 30 microS of conductivity). The test for these levels cost about $100/test (about 10 years ago).

    I would expect these chemicals to affect molluscs also (probably more so) so I would try using snails as a bioassay for the chemicals after you try to remove them.

    in reply to: Listen very carefully to my tale of waterchange woe… #355343

    BillT
    Participant

    Another possible problem associated with water changing is the introduction of supersaturated water to your tank.

    This can happen if your tap water is coming to your house cold in the pipes under pressure. Large amounts of trapped air in pipes can be forced into solution in the cold water because cold water can hold much more dissolved gas than warm water can.

    If you want to get an idea of how much gas can be dissolved in cold water, consider what happens when you drop a Mentos into some Pepsi.

    Taking the water out of the pressurized environment of the pipes and then warming it up will result in the excess air in the water coming out as small bubbles, either in the water, on surfaces or in the tissues of fish. CO2 is a special case but it gets the idea across.

    Besides seeing bubbles, you may notice the fish may going down to the deepest part of the aquarium where the water pressure is greatest. This will somewhat counteract the forces driving bubble formation in their tissues.

    Aeration will help remove excess air from the water in the aquarium. Spraying the water (lots of surface area and turbulence) before putting in to the aquarium can reduce supersaturation.

    Larger water changes can make the effects of this condition worse since there is more supersaturated water going into the aquarium and less normal water to dilute the excess air in the supersaturated water.

    This is often more of a problem in the winter when tap water gets cold before getting to your home.

    in reply to: Internal parasites?? #355089

    BillT
    Participant

    Mike is right. Both of these diseases can be carried by a fish without symptoms.

    Mycobacteria is NOT a obligate pathogen. It can survive without a host in an aquarium.

    Microsporidia can exist as spores out side of a host (but for how long I don’t know.

    I don’t believe either can be really treated well.

    Both may be (but not always) without symptoms until they are stressed in some way.

     



    I would remove affected fish. Probably all the fish of the affected species.

    Remove any dead fish immediately. Eating dead fish is thought to be an important (but not the only) way Microsporidia is transmitted.

    If I were concerned about the other fish getting infected, I would put them in a new clean tank and strongly bleach everything in the infected tank. More bleach and longer soak times make for a stronger bleaching. I use a lot of bleach (10% of residential bleach, which is usually about 5-6% bleach) for hours or days if I want to nuke something.

    Things like nets that can not be bleached (because they will fall apart) might be treatable by other methods (like iodine or maybe a good net dip if it exists). Alternatively you could autoclave (high heat and pressure) them. Not everyone has an autoclave, but a pressure cooker does the same thing. Some nets have parts that will melt. Try one wrapped in foil to contain the possible melted plastic. Dry materials at the top pressure cooker temperature and pressure for 15-20 minutes will probably kill everything.

    Using a UV “sterilizer” (irradiation level as described in the article above) can help because it can kill circulating spores and bacteria. I use UVs on recirculation systems of several tanks but not single tanks or tanks on flow though water systems. Keep UV bulbs up to date. Their output goes down over time and they should be replaced every 6 or 12 months depending on how how much dose you want and how fast their output goes down. The bulb manufacturer should be able to provide info (probably on their website) on the rate of decline of the bulb’s output.

    Both of these pathogens have been removed (with great effort) from very large operating research facilities, but it takes a few generations (fish generations) and molecular screening to identify carriers to do it. Most places don’t. They do things like trying to clean up their tanks and water systems, clean all the eggs laid in the facility with something like bleach (problem is bleach will kill the eggs at high enough levels to kill all the pathogens). Alternatives to beach being tested include iodine and hydrogen peroxide. Controlling the pH during these treatments can also affect the outcomes, but I don’t remember the details. These would all require testing before using. Bleach for example comes in different concentrations and different purities. Cheap bleach, presumably with impurities is much more lethal to fish eggs than more pure research bleach. For egg bleaching, I use bleach from Sigma chemical supply company (which is up around 10%).

    in reply to: Internal parasites?? #355086

    BillT
    Participant

    True. Its not uncommon for Mycobacteria to show large red lesions on the skin and sometimes diffuse red areas like around the nose (in zebrafish anyway).

    in reply to: Internal parasites?? #355080

    BillT
    Participant

    This sounds like to could be a microsporidia (Pseudoloma neurophilia) infection. This is a chronic problem in zebrafish labs and has been the subject of a fair amount of research (see link below). It has also been found in zebrafish from a lot (but not all) of fish farms that supply fish stores. It is not clear how widely among fish species this parasite be infective, but it can infect several danio species.

    It is slow acting and takes a while to spread

    Alternatively, it might be Neon Tetra disease (Pleistophora hyphessobryconis), which is also a microsporidian.It has been found in zebrafish and a several other species (tetras, zebrafish, barbs, goldfish).

    These are weird parasites that mostly lives inside of cells of the animals it is infecting. It is only found as a highly resistant spore outside of cells.

    There is not yet an effective treatment for infected zebrafish.

    Here is a link to description and details.

    in reply to: Zootaxa 3994(1) #354992

    BillT
    Participant

    I downloaded it too. 

    If you get the cartographer module, you can plot specimens or species on maps also.

    in reply to: Zootaxa 3994(1) #354976

    BillT
    Participant

    I looked into this a bit last might.

    Mesquite is the successor to MacClade. It is free, but I am not familiar with it.

    It should be able to export trees in a variety of formats.

    in reply to: Zootaxa 3994(1) #354974

    BillT
    Participant

    Some sites do assign individual identifiers to species, e.g., GBIF, whereas others such as Fishbase don’t.

    Must be annoying to have to changes names for them!

     

    Agree that it would be useful to have a universal system but think it might be a little beyond our remit to get involved in that?

    Yeah, it probably a job for the taxonomists, but I am quite willing to advocate for it. I just don’t know who to start with.

     

    Would love to include stuff like tree diagrams on the site, but don’t know how to construct them. Any advice?

    Can’t say I have it all figured out.

    I have drawn lots of trees by hand but it is kind of slow for a site this big. I have used MacClade in the past, but that program is now defunct and I am unfamiliar with its successor. There are probably other programs like it but I am not aware of them. There are algorithms for drawing them (I have a paper on a really old one) and a format for representing (normal not anastomosing or reticulate) trees as a nested series of parentheses. I think this might be how tree information is passed between programs that analyze these things. These text files could be converted into trees with the proper code. Creating the text files could be more tedious than the drawing the trees, but they might be obtainable from supplementary information for papers.

Viewing 15 posts - 1 through 15 (of 154 total)