-------- Original Message --------
From:
[email protected]
Sent: Saturday, January 05, 2008 11:13 AM
To:
[email protected]
Subject: archerfish, mollys, and marine tanks
Crew.
<Bob,>
I was having discussion on whether archerfish could tolerate full marine salinity. Not being any kind of expert with any knowledge of archerfish I found this link:
http://www.naturia.per.sg/buloh/verts/archer_fish.htm
Which stated:
"Breeding: It is believed that only the juveniles are found in brackish water
while the adults are more solitary and swim out to the coral reefs to breed.
20,000-150,000 eggs are laid. Only a few reach maturity in 1-2 years. Young
fish have iridescent yellow patches on their upper body between the dark
bands, which perhaps helps them to school together in the muddy waters. As they
get older, patches disappear and the black bands get shorter and eventually
only seen on the uppermost part of the body"
<Hmm... the breeding behaviour of all members of the Toxotidae is very obscure. The story that they breed on coral reefs, or at least in the sea, has been around for a while and may well apply to Toxotes chatareus and Toxotes jaculatrix. But field observations are lacking, and it certainly isn't true for the freshwater species such as T. blythi that live far inland.>
So I guess so.
Another person posted this from wetwebmedia page:
http://www.wetwebmedia.com/BrackishSubW ... stems.htm_
<This would be me.>
"Low salinity brackish water can be defined as water with a specific
gravity (or SG) between 1.002 to 1.005. Two sorts of fish can be kept in low
salinity water: true brackish water species that need slightly brackish water, and
species that are really freshwater fish but happen to be tolerant of
slightly brackish water. Among the true, low salinity brackish water fish are orange
and green chromides, figure-8 pufferfish, pike livebearers, and knight
gobies. Freshwater fish that happen to tolerate brackish water include spiny eels,
kribensis, glassfish, the archerfish Toxotes microlepis, and Florida
flagfish. Bumblebee gobies and mollies are difficult to place in either group,
because in the wild both occur primarily in fresh water. However, in aquaria, they
seem to do better when kept in slightly brackish water."
<My article there refers to Toxotes microlepis, a species that enters slightly brackish water in parts of its range but is otherwise a true freshwater fish. It tolerates low salinities, but as salinity goes up, becomes distinctly nervous and stressed.>
There would seem to be some inconsistencies between these two articles.
<Nope, not at all. They're talking about two different species. Simply because they're in the same genus, Toxotes, doesn't mean they have identical requirements. Indeed, what these archerfish effectively do is "divide up" ecological space between them. One species (T. jaculatrix) inhabits mangroves and river mouths, and the other (T. microlepis) lives in the river proper.>
Perhaps because the WWM article was aimed at people keeping brackish tanks. I
know from experience that mollys do better with brackish water but the article
is silent on full marine tanks.
<On the whole, Archers do not like to be kept in marine tanks. Toxotes chatareus and Toxotes jaculatrix can be kept best at SG 1.010 or thereabouts, and all the other species at less than SG 1.005, in some cases preferably in straightforward hard, neutral to alkaline freshwater.>
Mollys in my experience thrive and breed at
marine salinities. Some aquarium shops even use then to keep the bioload up
while awaiting shipments.
<Indeed. But this is different, because Mollies are hybrids, while Archerfish are rather a selection of species that come from different habitats. Toxotes chatareus, Toxotes jaculatrix, and T. microlepis are all widely traded but rarely identified correctly by retailers. Telling them apart is important if you want to optimise living conditions, though SG 1.005 will suit them all just fine if you can't separate them.>
I just wondered what your thoughts are and whether archerfish can be kept at
marine salinities.
<There's no real advantage to doing this, and unless you can securely identify the specimens in your tank, I wouldn't risk it. Stick a freshwater archer in a marine tank and you'll probably kill it. At the very least, it won't be very happy.>
Bob
<Cheers, Neale.>
