(Glossogobius giuris) is a freshwater fish native to Mainit Lake. It is called “biya” in Tagalog and “white goby or tank goby” in English. The term “pidjanga” is also sometimes fondly used to refer to the Mainitnons, the people of the Municipality of Mainit, a town in Southern Philippines. This blog hopes to capture potentials of Migrants Pidjangas for the Development of our Town by attempting to document development issues, folk stories, and current concerns, about the Pidjanga — both the fish and the people.

Lake Notes: Secchi Disk

Here's a note about Secchi depth measurements as supplement to the 7 August 2006 post: Lake Mainit... Philippines' MOST TRANSPARENT Lake

In 2004, Lake Mainit grabbed the Philippine record of 6.65 m Secchi depth and declared as the Most Transparent Lake in the Philippines.

Source: LaMotte Company

The Secchi Disk provides a very simple means of making transparency determinations in natural waters. Water that is clear has a high transparency. Transparency usually decreases in the summer when plankton, silt and organic matter are more likely to be prevalent. The most transparent lakes are usually seepage lakes as this characteristic greatly reduces the amount of silt bearing influents. Drainage lakes carry more silt and usually are less transparent. For example, a drainage lake may be in a class of 1.0 to 1.4 m but a seepage lake in the same area may give readings of 3.0 to 4.0 m. A high reading in the class of 19 to 21 m would indicate extreme clarity. That same lake in the summer may read only 10 m.

The Secchi Disk is a black and white circular plastic plate, 20 cm in diameter. A measured line is attached to the center of the disk by means of a special fitting that stabilizes the disk so that it will be parallel to the surface. Best results are obtained in the shade of a boat or dock. The best readings are usually obtained after early morning and before late afternoon.
1. Lower Secchi Disk into water until it just disappears. Read depth from calibrated line.
2. Raise Secchi Disk until it just appears. Read depth from calibrated line.
3. Add readings from Steps 1 and 2. Divide by 2. Record as Secchi Disk Transparency.

LaMotte CompanyHelping People Solve Analytical Challenges ®
PO Box 329 • Chestertown • Mary land • 21620
800-344-3100 • 410-778-3100 (Out side U.S.A.)
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Photos: and
By: Zimmbodilion Y. Mosende
Sep 26, 2006

1 comment:

Pidjanga Blues said...

LaMotte product distributor in


Dakila Trading Corporation
208 Pilar Street
Mandaluyoung City, Metro Manila
Tel: 63 2 724 7511
Fax: 63 2 721 0739
Contact Name: Richard Tee

Maradjao karadjao, Pilipinas!

Welcome to the online home of the Pidjangas from the Municipality of Mainit, Surigao del Norte, PHILIPPINES . Pidjanga, Pedianga, Pijanga, Pedjanga... amo ra ton... gikan sa ato danao! For comments and suggestion contact me at

CBCP News: Mining threatens 4th largest freshwater lake in PH

SEVEN are in the town of Mainit, Surigao del Norte... of the 15 exploration permits (EP) that the Regional Office 13 (CARAGA) of the Mines and Geosciences Bureau (MGB) of the Environment department approved as of June 30, 2010.

Read more at and Surigao Today.

If you want to support the protection of Lake Mainit, contact me at pidjangaATgmailDOTcom or 0917-800-4557. Zimm/Peter/Pidjanga

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