Periophthalmus kalolo, gen., ID, Sys.   12/12/07
Greetings from Alaska...
<And likewise from England,>
I just returned from visiting relatives in Fiji. I also regularly visit American and Western Samoa, both for business and pleasure. I have a few questions concerning Mudskippers:
<OK, fire away!>
(1) The species I've observed in both Samoa and Fiji I've tentatively identified as Periophthalmus kalolo. However, in Western Samoa and Fiji I've seen larger specimens with somewhat different pattern--the most numerous animals are small (2-2.5 in), beige ground color with chocolate brown irregular cross-bands. Larger animals (5-6 in) lack the
cross-bands, having a poorly defined pattern of darker blotches and whitish speckling on a light brown ground color. Does this represent more than one (sympatric) species, or merely ontogenic pattern changes?
<Not sure about this. Periophthalmus argentilineatus is also known from both Fiji and Samoa. Both species are pretty similar, though Periophthalmus argentilineatus is slightly larger and has a series of short silvery vertical bands on the lower half of the body, just above the anal fin. Both species have reddish dorsal fins, speckles on the flanks, etc. and it is common for multiple Mudskipper species to live in the same place. To be 100% sure what species you have, I'd recommend sending photos to Richard Mleczko, who wrote the Mudskipper chapter of my brackish aquarium book, and has kept and caught just many different species. His web page is at the link below:
http://homepage.mac.com/nmonks/mudskippers/goby.htm
His e-mail link is on that page. There is also an excellent section on mudskippers in the Aqualog book by Frank Schaefer. Both his book and mine actually have correctly identified Mudskipper photos, something not at all standard in the aquarium press!>
In American Samoa, I've only seen the smaller version in brackish mangrove streams and swamps. In Western Samoa and Fiji I've found both small and large specimens, always inhabiting mangrove stands in full seawater. Do you agree with my species identification?
<Impossible to say: the silver bands on the ventral surface is the only useful distinction, and you haven't mentioned these. Do also bear in mind that male and female Mudskippers can look very different.>
(2) I have several mangrove rhizomes currently growing in full saltwater (same as the habitat from which they were taken). They've begun to sprout roots, but no leaves yet. My hope is to establish a large marine tank for the mangroves in one of the deep-set windowsills in my house (long Alaska daylight enables tropical plants to thrive, believe it or not), along with halide lighting and a heater to make suitable habitat for mangroves, small fiddler crabs, Periophthalmus, Gobiodon, Brachygobius and possibly a small Pseudomugil species.
<Brachygobius spp. don't like seawater. The traded species in the hobby are really freshwater fish in the wild, and while low-end brackish water suits them very well in captivity, they certainly don't need to be kept in very salty water. While I've heard the odd story of people acclimating them to marine conditions, I've also heard it go wrong, and the poor little fish die. Surprisingly to some, Brachygobius spp. can be found in soft, acid blackwater streams in their native habitat!>
Concerning the latter, I'd like to try P. gertrudae, because they're small. My question is, are they strictly freshwater, or can they thrive in saline water as can some other species in the genus?
<Pseudomugil spp. -- known as "blue-eyes" in the trade -- include freshwater, brackish water, and salt water species. While I dare say freshwater species will tolerate low-end brackish conditions around SG 1.003, I wouldn't attempt keeping them in anything more saline. Pseudomugil gertrudae in particular is found in soft, acidic water conditions. If you want something small and colourful, you'd be better off with a brackish water killifish or livebearer of some type, perhaps Micropoecilia picta.>
(3) The set-up I envision (will probably have to get a local Plexiglas outfit to construct it for me) is to make an approx. 72" x 24" x 24" tank with three screened standpipes of different heights at one end to simulate tidal changes--check valves on each one so water level can be changed manually. Stand pipes emptying into another, comparably-sized tank on the floor (which might be dedicated only to filter media).
<Sounds great, but Mudskippers at least couldn't care less about salinity variation. They adapt very well to fixed salinity environments, ideally around SG 1.010 though slightly above or below is acceptable.>
Siphon from a large canister filter to draw water from the lower tank, with the outflow pipe attached to the end of a Plexiglas "planter" at the back of the upper tank, in which a bottom compartment of about 3-4" depth is covered with a fitted plastic screen. Over this will be planting substrate and the mangroves. The idea is for the water to cycle up through the mangrove planter, and then into the tank, thence through a standpipe back down to the lower tank, etc.
Do you think this set-up will work?
<I'm no plumber, but the theory sounds good. As I say though, it isn't the sort of project I'd engage with just for the sake of the Mudskippers. They spend 90% of their time on land, ideally on sand or flat rocks or smooth bogwood, so what they really want is a complex terrain made up of those materials. Some burrows are also appreciated (PVC pipes stuck into the sand are ideal). Beyond that, a pool of water for bathing is all they require. They are actually extremely hardy and adaptable fish; the reason they have a mixed reputation in the hobby is solely because people try to keep them in freshwater or marine tanks, neither of which are acceptable. They want a brackish water vivarium.>
I guess I'd have to fill the bottom tank and start cycling the water when the lowest stand-pipe is open to avoid overflowing the bottom tank. I've also thought of setting up the lower tank with anemones, soft corals and a few Amphiprion, Dascyllus and Chrysiptera.
<No. Don't do this. If there are aggressive or large fish in the water, the Mudskippers won't go swimming. This causes problems. Mudskippers inhabit areas completely devoid of other fish, i.e., dry land. They can't and won't deal with active or territorial fish. Ideally, Mudskippers should be kept alone. Small fish can be viewed as food, hence my recommendation to with livebearers, so that you can at least expect the population to sustain a certain amount of predation. Fish of similar size to the Mudskippers terrify them. In the wild, when they see fish in the water, they stay on land or go into their burrows.>
(4) Are P. kalolo imported to the US? It probably wouldn't be difficult for me to get a collector's permit in Fiji (or in Samoa), but a lot of hassle to get the animals into the states, which I would prefer to avoid.
<It may be imported occasionally but it isn't a staple. For the North American market, the trade is dominated by Periophthalmus argentilineatus and Periophthalmus barbarus, and sometimes Periophthalmus septemradiatus, at least according to Richard. European aquarists additionally get a "dwarf" (~6 cm) species known as the Indian Mudskipper, likely identical with or related to Periophthalmus novemradiatus. Periophthalmus barbarus is the one to avoid if you can, partly because it is huge (~20 cm) but mostly because males are unbelievably aggressive and will sometimes kill everything in the tank kept with them! In any event, none of the retailers seem to identify Mudskippers properly, so the best you can do is consult a reliable book and identify the Mudskippers yourself.>
Sorry for the length of the e-mail, and thanks in advance for our
consideration.
Sincerely,
Fred
<Hope this helps, Neale.>

Re: Periophthalmus kalolo -12/14/07
I have relatives in England (unfortunately, I've never met any of them). One of note, who passed on several decades ago, was a distant cousin, Abdullah Archibald Hamilton.
<Very interesting. One of the more famous converts to Islam, and a noted (and aristocratic) statesman of note.>
Then I'm fairly certain that's what the larger specimens were--I saw one identified as P. argentilineatus in the Sydney Aquarium while visiting my son there in 2005. I wasn't noticeably different than the animals I saw in W. Samoa and in Fiji.
<The two species, P. kalolo and P. argentilineatus, are very similar, but once you know how to tell them apart (and assuming the fish are mature) then distinguishing them by eye should be possible.>
I did notice poorly-defined ventro-lateral (silver) markings on one of the larger specimens I caught and took into the vali house so my granddaughter could see it. Also learned that, while nearly impossible to catch during the day, both species are easily caught by hand at night when dazzled with a hand-torch (flashlight).
<Interesting.>
Thank you for the references! Unfortunately I took no photos, as I kept forgetting to charge my camera.
<Always the case.>
Yeah...I figured either that or ontogenic pattern changes. However, with the clues you've given I believe both species were present in both Viani Bay, Fiji, and in Vaigaga, W. Samoa. For aquarium purposes I'm only interested in the smaller P. kalolo.
<The size difference isn't all that great, and I'd be more worried about minimising the number of males in the tank than cherry-picking species.>
Aha--thanks for the warning. I'll have to set up a small separate tank for Brachygobius, then. I would like to, as my LFS regularly receives very large individuals with deep orange, rather than just yellow, bands. Very impressive. I'll add there is a possibility I'll be working in General Santos City, Philippines for a year--so I may get opportunity for first-hand observation of Brachygobius habitat preferences, God Willing.
<Very good. Goby taxonomist Naomi Delventhal, who wrote the Goby chapter in my brackish book, has taught me a lot about these fish. They are essentially indistinguishable to species level without examination under a microscope, hence my preference these days to refer to them as Brachygobius spp. rather than any one species. While most do occur in brackish water in parts of their range, something like half the species are found in freshwater habitats as well. My feeling is that most starve to death in aquaria, and the belief that the lack of salt is the issue is erroneous. A fascinating but misunderstood group of fish.>
Thanks again for the tip. I've read that P. cyanodorsalis and P. signifer are both found in full salinity water in the wild. The former species, being small and colorful, might work (a friend who owns a very good aquarium shop in Rockdale, NSW has told me this species has been tank-spawned). Your recommendation of small live-bearers reminded me that I already have a small population of Heterandria formosa. I "rescued" one gravid female from a "feeder" tank at the aforementioned LFS, and she has regularly given birth every few weeks since then. Heterandria live in brackish as well as fresh water--I've caught then in salt marshes in southern Georgia, USA.
<Indeed. Would work well with Mudskippers, though quite probably more as live food than anything else!>
Sorry, I wasn't clear in my previous e-mail. The variable-height standpipes are to raise and lower water level, not salinity, in imitation of tidal ebb and flow. I intend to keep the tank at fixed salinity.
<Ah, yes, this would be ideal. Richard Mleczko is a great fan of this sort of thing with Mudskippers. Not required, but looks very nice.>
That's the purpose for the standpipes--I hope to lower and raise water level from 14" to 8" to 4" and back again, keeping the water at each level for about eight-hour increments. I plan to have the mangrove planter at 12" height, so at the lower water levels there will be fairly extensive above-water substrate available (not to mention the roots I hope the mangroves will put down as they grow). Also, I brought back some hollow bamboo sections from the remains of a Viani Bay relative's old raft to facilitate burrow-making.
<Good. Do bear in mind that wood sometimes rots more quickly in saline water. No idea why, but does seem to happen.>
As far as I can tell, the animals I observed in W. Samoa and Fiji were in fully saline habitat (I just remembered seeing some near Savusavu, Fiji that were in a tidal creek, but the ones at my daughter-in-law's family's place in Viani Bay were in fully saline conditions--one could swim only a few yards out from the mangroves where the Periophthalmus were, and see myriads of reef fishes, including Gobiodon, Damsels, Lionfish, as well as soft and hard corals). There was no fresh water on the island, other than a large rainwater tank my daughter-in-law's relatives maintain for their needs. Having said that, it does seem best to opt for brackish conditions--hopefully, I can gradually reduce salinity to about 12-16ppm without harming the mangroves, once these have become established.
<The precise salinity isn't important. Mudskippers are perhaps best thought of as "tidal" rather than brackish water fish. So yes, if the tidal water is marine, e.g., a rocky reef along a beech, then yes, they'll be in more or less normal marine salinities. But they are also common in tidal brackish water environments, and the lower cost of maintaining them thus can be beneficial to the aquarist! Lower cost = cheaper water changes = more water changes = better water quality. Reduced salinity also places less stress on their osmoregulatory system, and is also less likely to be acceptable to marine or freshwater parasites. The one thing they don't like is freshwater. I'm not aware of any true mudskipper than tolerates freshwater indefinitely.>
Sorry, I wasn't clear again--the damsels would be kept in the second, lower tank (into which the standpipes from the Periophthalmus tank would empty). They would not come in contact with the mudskippers. But, if I reduce salinity to about half seawater as you suggest, I won't be able to keep marine damsels anyway.
<There actually are several brackish water damselfish, usually sold as "freshwater damselfish" even though they don't do especially well in freshwater conditions. See here:
http://homepage.mac.com/nmonks/aquaria/brackfaqpages/Marine_fish/(7e)damselfishes.html
Most hardy marine damsels, like Sergeant Majors for example, will thrive at SG 1.018 too, and could be used.>
However, there are several outstanding N. American small brackish spp that would thrive, such as Adinia xenica, Fundulus rivulus, Cyprinodon variegatus, Poecilia etc. I kept two 55gal housing populations of these and other N. American brackish spp for about seven years back in the mid '90s. The fishes I released when I disassembled the tanks were the several-times-removed grandchildren of the original stocks.
<Poecilia spp. especially work well with Mudskippers. Wild-caught Mollies for example make nice additions.>
I have noted their apparent fear of going too far from shore, and concluded this was due to fear of predation.
<Precisely. Mudskippers are very good jumpers on land, and rely on that to avoid predation from terrestrial predators. But in the water they are poor swimmers. So they don't like being in water where there are other fish of similar or larger size.>
I attempted to keep 7 specimens of a W. African species--considerably larger than P. kalolo--back in the early 90s, with moderate success.
However, they were vicious, and their powerful jaws made short work of any fish, crustacean or insect placed in their tank (and occasionally each other). I had identified them to species, but don't recall it now--the males in particular had blue and red bands on their dorsal fins (very similar to those on a Rainbow Darter--Etheostoma caeruleum--a species which I currently keep).
<Those are definitely P. barbarus. The males have brilliant red/blue dorsal fins. But as you say, this species is incredibly vicious and highly predatory. At least in the UK, this species is now very rarely traded, the "dwarf" Indian Mudskipper species being a far nicer aquarium fish.>
Yep.
Sorry for the earlier "jumbled" reply--hope this comes out better.
Sincerely,
Fred
<Glad we could help. Please do get in touch with Richard; he really knows his stuff when it comes to 'Skippers. Cheers, Neale.>