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Perfect Pods

This topic contains 1 reply, has 2 voices, and was last updated by  Pete Giwojna 1 month ago.

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  • #39729

    donsods
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    Pete—the care sheets recommendation supplemental feeding captive bred pipefish with Nutramar Tig pods. Are Tig pods a little big for pipes and Erectus , especially early on when they are not full grown? I am looking for a pod species to culture in anticipation of getting both pipes and Erectus. Any suggestions?

    #39769

    Pete Giwojna
    Moderator

    Dear Don:

    Yes, sir, the Tig Pods may not be the best choice for culturing, especially for small/young seahorses and pipefish.

    There are three major groups of free-living copepods that are useful in aquaculture (Dürbaum and Künnemann, 2000): the Calanoida (primarily free-swimming planktonic animals), the Cyclopoida (either planktonic or demersal), and the Harpacticoida (entirely benthic). Of these, Harpacticoid copepods such as Nitokra lacustris are most commonly cultured as fry food.

    Copepods at the right stage of development are the most nutritious food that seahorse fry can eat. Marine copepods are the ideal food for rearing seahorses fry. They are a natural prey item that constitutes a large portion of the diet of fish larvae in the ocean, and many marine fishes have evolved efficient feeding strategies for preying on them as their primary foods. This includes seahorses, whose tubular snouts are adapted specifically for feeding on tiny crustaceans such as ‘pods, and which have developed a sedentary lifestyle as ambush predators that allows them to capture them with maximum efficiency and a minimum expenditure of energy. The tiny size of the copepod nauplii allows even the smallest seahorse fry to eat them, and they are a feed-and-forget food that will survive in the nursery tank until eaten. The distinctive swimming style of copepod nauplii triggers a strong feeding response from seahorse fry, and ‘pods have naturally high levels of essentially fatty acids. Best of all, as a natural prey item the copepods are easier for baby seahorses to digest than newly hatched brine shrimp, which maximizes the nutritional value of the copepods. They are superior to rotifers in all these respects (seahorse fry often reject rotifers because they don’t move in the “right” way and simply don’t trigger their feeding instincts) and I recommend that aquarists who are raising pelagic fry concentrate on culturing copepods.

    Seahorse fry alter their diet as they grow (Vincent, 1990). This may be due to the fact that they change microhabits as they develop (e.g., when pelagic fry complete their planktonic stage and begin to feed at the bottom as they begin orienting to the substrate). Or it may simply be due to the fact that they become better hunters and perfect their feeding skills as they grow, thus enabling them to tackle larger, more active prey (Vincent, 1990). Whatever the cause, one good way to keep up with the fry’s changing dietary requirements is by providing them with cultured copepods at progressively later stages of development. The first step in culturing rotifers or copepods is to establish a good culture of marine microalgae or phytoplankton.

    Step 1: Providing Marine Microalgae (Phytoplankton).

    Marine microalgae or phytoplankton is available from many sources. It can be cultured at home, and if you have a green thumb and are experienced with such greenwater cultures, that may be your best option. However, home culturing may not be for everyone. Greenwater cultures can be tricky to maintain. They are easily contaminated and are prone to “crashing” suddenly and unpredictably, which can have dire consequences if you are relying on the phytoplankton to provide food for your seahorse fry.

    Alas, I am one of those unfortunates who cannot seem to maintain a decent greenwater culture for any length of time no matter what I try. Consequently, I now much prefer to obtain live marine phytoplankton from other sources rather than attempting to culture my own. Commercially available phytoplankton tends to be more concentrated than homegrown cultures as a rule, and I find purchasing it to be far more convenient, efficient, and productive. Given my repeated failures and the time I spent for naught on my own greenwater cultures, I’m certain that buying live phytoplankton is more economical for me in the long run as well. If you are inexperienced with greenwater culture or simply lack the time to culture your own, I recommend buying your live phytoplankton instead (see the Resources page for suppliers). Whichever source you decide to use, home grown or store bought, make sure you use it strictly according to instructions to prevent contamination and spoilage of the phytoplankton.

    The type of phytoplankton or microalgae you use is not that crucial. Chlorella is one of the most popular microalgae used in mariculture (Wilkerson, 1995), but Dunaliella also works extremely well and is recommended by Dr. Amanda Vincent (Vincent, 1995c), an authority on the breeding habits of seahorses. Serious breeders often use a mixture of different types of phytoplankton to feed copepods or rotifers, rather than a microalgae monoculture, with the goal of enhancing the nutritional profile of the ‘pods or rotis as much as possible (David Warland, pers. com.).

    There is a great deal of merit to that approach, but in the past, maintaining separate cultures of different species of microalgae was beyond the capabilities of most home hobbyists, myself included. I prefer to keep things simple and I have always used Nannochlroposis as the phytoplankton I feed to copepods, both because it produces good results and because it is commercially available from a number of sources. To simplify things all the further, I purchase my Nannochlroposis in quantity as needed, rather than struggling with phytoplankton cultures.

    The product I like best at the moment for this now includes a concentrated mixture of live marine phytoplankton (two species of Nannochlroposis, N. oculata and N. salina, as well as a Chlorella sp.) in every bottle (DT’s Live Marine Phytoplankton, 2003). That makes it a simple matter to provide my ‘pods with a diversified diet to maximize their nutritional value as fry food — I just unscrew the cap on the bottle and pour the requisite amount of this phytoplankton mixture into my culture tank whenever it’s losing its greenish tinge, and I’m in business (DT’s Live Marine Phytoplankton, 2003)! No muss, no fuss. Quick, easy and effective — just the way I like it!

    Step 2: Culturing Zooplankton (copepods and/or rotifers).

    We will be using standard 10-gallon glass aquaria as our batch culture tanks. It’s a good idea to run at least 2 such tanks simultaneously; that way, if one of the cultures falters, the other tank can pick up the slack and you won’t miss a beat. Depending on how many seahorse fry you are rearing, you many need to operate several such tanks to assure you will be producing sufficient food for them all.

    Fill each of these culture tanks slightly less than half full with synthetic saltwater, adjust the salinity of the culture tank to match the salinity of your nursery tanks, and maintain the pH at 7.9 or below (Rhodes, 2003). This will assure that the copepods (or rotifers) we are culturing do not experience any salinity shock when we feed them to our seahorse fry. No heater is necessary — the cultures will do just fine at room temperature (24C-28C is optimum). Provide very low aeration (Rhodes, 2003). Airstones are unnecessary — a naked bubbler stem is sufficient. Adjust the airflow so it produces a slow, steady stream of coarse air bubbles (slow enough so that you can count the individual bubbles). Ambient room lighting is adequate or you may provide low wattage fluorescent lighting if you prefer.

    Add enough greenwater (either commercially produced phytoplankton you’ve purchased or your own homegrown microalgae) to tinge the culture tanks green, and you’re ready to start culturing copepods. All that remains at this point is to “seed” the culture tanks with copepods. Add a starter culture of marine copepods to each tank, acclimating the ‘pods if necessary exactly as you would acclimate a new aquarium fish. They will do the rest.

    To nurture the copepods, simply maintain a nice green tint to the culture water by adding more phytoplankton whenever the water in the tanks begins to clear in color. (Be conservative with these phyto-feedings. One dose of phytoplankton every 7-10 days is generally adequate, depending on production and your copepod harvest rates; Rhodes, 2003.) The ‘pod population in the culture tanks will double every 2-3 days, depending on the temperature and how well they are fed (Rhodes, 2003), and as soon as the population builds up sufficiently, we can begin to harvest copepods to feed to our seahorse fry. When you begin to notice numbers of copepods gathering on the tank glass, that’s a good indication that their population density can support daily harvesting.

    The best way to harvest copepod nauplii is to strain the desired amount from the culture tank using a 35-micron sieve and then rinse or backwash the strainer in the nursery tank (Rhodes, 2003). Alternate which culture tank you harvest the copepods from for each feeding in order to avoid depleting the ‘pod population too much in any given tank.

    Periodically, it will be necessary to restart the copepod culture tanks to filter out the detritus that accumulates on the bottom. This is typically done every month or two (Rhodes, 2003) and is a surprisingly simple process. Just siphon out the water from the culture tank, straining the water in the process in order to retain the copepods. A 125 -micron sieve works well for a strainer. That size mesh will retain all the reproductive adults you need to restart your culture (Rhodes, 2003). It’s a good idea to use a small diameter siphon at first, being careful to suck up as little of the detritus as possible since it will clog up your strainer and your goal at this point is to recover as many copepods as you can. Once you’ve strained out most of the ‘pods, backwash them into container of clean saltwater and set them aside to seed the culture tank after you’ve finished cleaning it. Having saved as many pods as possible, switch to a larger siphon and drain the culture tank completely, removing all of the accumulated detritus. Fill the tank half way with freshly mixed saltwater you’ve prepared in advance and adjust the aeration. Then return the copepods you strained out previously and add enough concentrated phytoplankton to tinge the water green, and your culture is ready to begin producing again. If you restart your culture tanks on alternate months, one or more of them will be in full production at all times, and you can keep a thriving copepod population going indefinitely in this manner.

    Suitable plankton screens can be purchased from Miami Aquaculture Inc. (see the following link):

    http://www.miami-aquaculture.com/screen.htm

    I would recommend about of 38 micron screen for harvesting copepod nauplii in the first or second instars and a 110-125 micron screen for gathering large pods.

    If you so desire, rotifers can be cultured in exactly the same manner. The only difference is that the 10-gallon culture tanks should each be seeded with a quart of live rotifers initially (Giwojna, Jan. 1997). When necessary, add enough concentrated phytoplankton or greenwater to keep the rotifer culture tanks slightly green. As long as the rotifers are being fed algae, about 25% of the rotifer cultures can be harvested each day to feed to your seahorse fry (Wilkerson, 1995). Try to keep more than one rotifer culture going at all times in case of crashes, and be sure to keep the bottom of the culture tanks scrupulously clean (Giwojna, Jan. 1997).

    In fact, you can even maintain a dual culture of copepods and rotifers in the same tank if you wish. But you must avoid cross-contamination of your culture tanks with brine shrimp at all costs! Newly hatched brine shrimp (Artemia nauplii) are considerably larger than either copepods or rotifers, and the Artemia will happily fed on them as well as the phytoplankton. So if any brine shrimp ever find their way into your culture tanks, you will very shortly thereafter be culturing Artemia instead of ‘pods or rotis, leaving you with nothing but live food that’s too large for pelagic fry to eat.

    Harpacticoid copepods such as Nitokra lacustris go through 6 naupliar stages as they grow, followed by 6 copepodite stages, before they become reproductive adults. They range in size from 45 microns (smaller than rotifers) up to 270 microns as full-sized adults. The many different stages of development copepods undergo is actually a blessing for the aquarist since it makes it possible to provide progressively larger ‘pods to the seahorse fry as they grow simply by using sieves with different sized mesh to harvest them. For instance, a 35-micron sieve will gather up even the smallest copepod nauplii for newborn fry, while a 125-micron will collect only adult-sized pods for older fry and juveniles, leaving the smaller ‘pods behind to develop further. An 80-micron sieve will take intermediate-size ‘pods along with the adults.

    Whether you’re culturing rotifers or copepod nauplii, pelagic seahorse fry should be fed continuously starting 6-12 hours after birth (Giwojna, Jan. 1997). Dr. Amanda Vincent recommends feeding 2 plankton nets of rotifers (or ‘pods) 5-7 times daily or whenever no plankton is visible in the nursery tanks (Vincent, 1995c). In addition, she keeps a drip of diluted plankton (i.e., rotifers or copepods) going at the rate of 10 liters/day at all times (Giwojna, Jan. 1997). (A bucket of copepod-laden or rotifer-rich saltwater set on top of the nursery tank will suffice for this–just use a length of airline tubing as a siphon and adjust the drip rate with a valve; Vincent, 1995c.)

    For more information on these culture techniques, please refer to the Plankton Culture Manual published by Florida Aqua Farms, Don.

    This is normally what I advise home hobbyists regarding the value of marine copepods for seahorse fry, sir:

    MARINE COPEPODS

    Pros:
    · Naturally high levels of essentially fatty acids.
    · Natural food that forms a large portion of the seahorses’ diet in the wild.
    · Elicits a strong feeding response.
    · Perfect first food for seahorse fry.
    · Feed-and-forget: marine species survive until eaten and will colonize live rock, filters and refugia.
    · Starter cultures readily available.
    · Easily collected by hobbyists with access to the seashore.

    Cons:
    · Complex life cycle complicates home culture.
    · Many species too small to interest adult seahorses.
    · Some species are parasitic — can be difficult to tell the good guys from the bad boys.

    Collecting Tips:
    Free-swimming copepods can easily be collected by anyone who lives within a reasonable distance of the ocean (in parts of the sea, larval calanoid copepods comprise the bulk of the zooplankton). Simply tow a plankton net (an elongated conical net made of fine material) slowly behind a boat in an area well away from possible sources of pollution, stopping periodically to empty its contents into a collecting container. (A mesh size of 250-500 microns will collect ‘pods that are about the right eating size for medium seahorses.) Cover the collecting bucket with a damp towel to keep it cool during the heat of the day and provide aeration to make sure the plankters stay alive until you get home.

    Culture Instructions:
    Suitable for batch culture with greenwater (phytoplankton). See the rearing chapter of the Ocean Rider Seahorse Training Manual for complete directions for culturing copepod nauplii.

    Comments:
    Providing copepod nauplii as the first food for pelagic seahorse fry results in faster growth and often dramatically increases survivorship.

    Copepods are an extremely diverse group of Crustacea with more than 10,000 known species with different lifestyles filling a great variety of environmental niches, both marine and freshwater (Dürbaum and Künnemann, 2000). There are three major groups of free-living copepods that are useful in aquaculture (Dürbaum and Künnemann, 2000): the Calanoida (primarily free-swimming planktonic animals), the Cyclopoida (either planktonic or demersal), and the Harpacticoida (entirely benthic).

    Copepods undergo a remarkably complex life cycle. After hatching from the egg, they pass through six distinct nauplius stages, undergo a metamorphosis that completely transforms their body shape, and then go through six additional copepodid stages, culminating with the mature adult (Dürbaum and Künnemann, 2000). The first nauplius stages have only 3 pairs of appendages, which are used for locomotion and feeding (Dürbaum and Künnemann, 2000). The 6th and final naupliar stage molts into the first of the copepodid stages, and important development marked by major morphological changes (Dürbaum and Künnemann, 2000). The emerging copepodid larvae resemble the adults in large part. With the increasing number of body segments in the copepodid, more of their appendages become fully functional (Dürbaum and Künnemann, 2000). After the fifth copepodid molt adulthood is reached and the mature copepods are able to reproduce. There are two different sexes and reproduction is sexual (Dürbaum and Künnemann, 2000).

    Growth is very rapid, with most species going from the embryo to mature adult in 10-12 days at 25-degrees C. The free-swimming nauplii are attracted to light, becoming less phototropic as they mature, until the adults begin to settle and attach to the substrate. As adults they swim less, remaining attached to substrates for anywhere from a few seconds to a few minutes at a time.

    Okay, Don, that’s the quick rundown on copepods. If you send me a brief email off list to the following email address, I can provide you with a lot more information on different types of live foods that are useful for raising seahorses, including instructions on how they can be cultured: [email protected]

    Best wishes with all your fishes, Don!

    Respectfully,
    Pete Giwojna, Ocean Rider Tech Support

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