Estuarine Fishes of Singapore

Estuarine Fishes of Singapore

The main river of Sungei Buloh Wetland Reserve - Buloh Besar River during high tide.

Estuaries are where freshwater meets saltwater, creating habitats of varying tide and salinity levels revolving around brackish water! While many fishes that are found in estuaries are often marine fishes living out a phase in their lives before moving back out to sea, there is also an extensive variety of fishes perfectly adapted to different regions of the estuarine habitats Singapore has to offer.

Mangrove forests immediately come to mind. These coastal marvels serve so many ecological and environmental roles! For example, they are amazing carbon sinks and soften tidal impacts on inland habitats, all while serving as nurseries for juvenile fishes and stopovers for migratory birds. Mangroves used to make up 13% of Singapore's total land area in the 1800s but by 2018, it is down to only 0.5% (nearly 90% of the mangroves were lost due to development).

Today, conservation efforts are in force and restorations have been slowly regaining what we lost. The Sungei Buloh Wetland Reserve is one of our most precious estuarine spaces and is an important site for migratory birds that is recognized worldwide. Other popular mangroves to visit include Pasir Ris Park, Berlayer Creek and Admiralty Park.

One of the many mangrove creeks in Pasir Ris Park.

As mentioned earlier, the salinity and water levels influence the types of fish one might see. A visit with two different conditions can yield very different varieties! Some of the usual fishes spotted by nature-goers include the Banded Archerfish, Stripe-nosed Halfbeak, Spot-tail Needlefish, Spotted Scat and various mullets. These fishes are easy to spot and active in open water along the fringes of our estuaries and in tidal rivers, even swimming into into the mangroves during high tide. 

How can one forget the mudskippers as well? Species like the Giant Mudskipper are the first fishes to come to mind when the word "mangrove" is mentioned. They can be seen on open mudflats and even further inland during low tide, or taking shelter on elevated surfaces during high tide. 

A fishy sight! A school of Spotted Scats disturbing a school fo Spot-tail Needlefishes.

However, a closer look combined with a little patience and timing can reveal a lot more fishes even from above water! During low tide, various isolated pools are revealed alongside creeks of varying sizes. These are often home to the estuarine gobies (Gobionellinae) and also serve as temporary shelters for other fish such as the Javanese Ricefish until the tide rises again. Other mudskippers are also much easier to spot or exclusively found during low tide. 

Despite the general adaptability of estuarine fishes to salinity ranges, many of them definitely have their preferences. As one goes further inland (upper mangrove), the salinity decreases to near freshwater and different species can appear for example! 

Shallow pools revealed during low tide.

A typical scene during low tide in the mangrove forest. Even so, there were Giant Mudskippers burrowing!

An unsuspecting patch of mangroves on a breakwater that is still booming with activity.

Nipah Palms - an iconic mangrove plant in Admiralty Park's mangrove.

The muddy intertidal zone of Pasir Ris Park's mangrove fringes.

Estuaries are complex systems that deserve far deeper discussion beyond just biodiversity. What is clear here, however, is that the diversity of fishes found within them is truly eye-opening. These habitats are increasingly impacted by climate change, pollution, habitat loss, and other human pressures.

This blog aims to highlight the ever-growing list of estuarine fishes, so that future visits to our estuaries may be filled with a little more curiosity and appreciation for these often-overlooked ecosystems!

Want to check out what is available so far? Click here: https://sgfishesabovewater.blogspot.com/p/estuarine-fishes-directory.html