High pH C.A. biotope

[duanes]

Most aquarists know the natural waters in Central America are alkaline, mineral rich, and have a high pH. How high they can go may be a surprise.
Lake Bacalar in southern Mexico where Vieja, Crytoheros, and Thorichthys are found, pH ranges from 7.7 to 8.2
Lake Managua where many Amphilophines are found in Nicaragua can hit upwards of pH 9.3
Lake Nicaragua up to pH 8.9.
Cenotes in Mexico where Rocio and Thorichthys are found can vary seasonally pH 6.9 to 8.9.
I have collected cichlids in half dozen rivers in Panama and decided to to do a Mamoni river biotope, I have gone there on and off over the last few months and beside fishing, taken pH and nitrate readings.
In the dry season pH held around 8.2, but since the rainy season started pH has dropped slightly to 7.8.

The most common fishes in he river are tetras, outnumbering all other fishes by almost 25 to 1.
I have found Astyanax, Brycon, and Roeboides.

Catfish are also plentiful.
Pimleodellus, Plecos like Chaetstoma, and whiptails such sturosoma


Then there are the Gobys
Gobiomorus spAwaous banana (I believe)
And the 2 most commonly caught cichlids,

Darienheros calobrensis above.
Isthmoheros tuyrensus below.

So far no overt aggression.

All the above arenas in a 180 gal tank (except the tetras), due tother tendency for being Lernaea carriers, they will remain in QT about 3 months.
The flow of the river is quite strong, (lots of rai lately) and pH last tested about 7.8, and even though the water is the color of cafe latte, nitrate still undetectable.
.

 

[neutrino]

Example of something I've said about a lot of wild habitats, water conditions can change according to varying cycles, something many species of fish are adapted to over time and their geographic distribution.

 

[duanes]

A semi panoramic view of the 180 gal tank.
Because I allow, and encourage rain water flow into the tank from surrounding foliage, the tank water gets quite tannin stained this time of year.
(anything for an extra (albeit small) free, daily, rainy season water change)
Even as darkly tinted as it gets, pH has only slightly dipped from is normal pH of 8.2, to 7.8.

 

[duanes]

Another interesting feature I've noticed about many of the fish (living somewhat copasetically) in this small stretch of river, is their different mouth structures.
Which indicates they each have a separate feeding strategy, so do not need to compete, for similar resources.

In many cases (especially with cichlids) aquarist seem prefer a certain, genus, shape, a look, so will often combine similar species, that would not be found together in nature, and overt aggression ensues.

In this river, one of the Gobies is a piscivore, a predator, and their mouth structure obviously shows that

These gobies are the convergent equivalent of Crenicicla pike cichlids in S America, Parachromis in central America, or snakeheads in Asia, or Amia calve, and pikes or pickerel in North America.
The other species of Goby found here, has a totally different feeding regime, combing for edibles in the subsrate. Genus Awaous.

In their tank, I have not seen competition, or aggression between them.

The cichlids here in the Mamoni also have different mouth structures.

Darienheros above, a protractible mouth for picking and extracting invertebrates from between rocks, and also sand sifting.
Below Isthmoheros, a detritus, and vegetation feeder, with teeth that chop leaf litter, and the plants.

I have not yet seen any overt aggression between the 2 species.
I would imagine if I were to put Isthmoheros in a tank, with Vieja, north American sun fish, or south American Heros severus, the outcome may not be as benign.

 

[Omrit]

Those gobies are very cool. Awaous banana especially looks nice, face has a lot of character.

 

[duanes]

Yes the Awaous remind me of the new world equivalent to Asian mudskippers, just without propensity to climb on dry land.
Their geographic range is said to be as far north as Florida, south into Brazil.