Beware Of So Called “Brackish Water Plants”

Supershrimp tanks are great, almost no maintenance, decorative habitats for our beloved shrimp. Some people use rocks, others use plastic plants to decorate. But a large number of people want to know which live plants they can use in their Supershrimp tanks. So the first thing they do is to go on the internet and search for “brackish tolerant plants” or “brackish water plants”. Immediately they are bombarded with search results that seemingly indicate that there are lots of plants that can survive and thrive in brackish water. Specifically they find that java moss and java fern “do well” in brackish water. So they go out and buy these plants and throw them in their brand new Supershrimp tanks.

One of two things then happen:

1. Their shrimp start dying shortly after, or they start developing an algae or bacterial bloom.

2. They proudly come to the forum to announce after a week, a month, or several months that their plants are still doing great (but the problems start later for the second group and most of the time they don’t come back to report on the problems).

So what’s going on? Didn’t literally dozens of websites list these plants as perfectly fine in brackish water? Yes, they did. But they are *all* wrong. The myth that plants like java moss and java fern grow and thrive in brackish water is decades old. It’s something that is still being perpetuated by well-meaning but ultimately ill-informed *freshwater* aquarium keepers who have dabbled a bit in low salinity brackish water (usually up to around 1.004SG or 5ppt). What people have been doing for decades is throw some plants in brackish water and observe how some die immediately but others stay green for a long time. Some, like java moss, even grow a little at first at very low brackish conditions (1.004SG) before eventually dying. Upon observing that these plants stay green, the satisfied freshwater aquarist declares that the plant “does well” or is “brackish water tolerant” and spreads the info online or confirms one of the articles already spreading the misinformation. Have any of these people maintained a brackish water tank with a thriving and multiplying population of these plants? Of course not…

Here’s what’s really happening: Even at very low salinities those plants are dying or dead…even though they are still green. I have tested this theory in marine tanks with things like java fern and java moss and even “round pellia” (Suesswassertang), but also in long term tests with java fern at low salinities. Even in marine tanks the plants stay green for a very long time. Are they now reef tank tolerant too? Of course not. They are dead and will start polluting your tank.

How about “Marimo Balls”? Marimo balls are a species of filamentous algae (Aegagropila linnaei) with a worldwide distribution. It not only occurs in ball shape but more commonly attached as a carpet-like flat growth to rocks, or as free floating filaments in the water and on the substrate of mostly freshwater lakes. Some populations occur in brackish water, such as the flat, rock-attached growing form in the brackish Baltic sea. So, theoretically at least some populations (at least the flat growing, rock-attached ones) of this species should be adapted to brackish water, even though the ball shaped populations exclusively occur in freshwater lakes. Many of our forum members have tried growing Marimo balls in their tanks. Even though their marimo balls (mostly) don’t seem to die immediately and stick around for months or even a year+, they never appear to grow or multiply. Hence, it’s unlikely that the marimo balls commonly sold in stores and online are adapted to brackish water at the salinities at which we keep our Supershrimp.

Ok….so what plants CAN you keep in Supershrimp tanks?

The only plants, so far, that thrive and reproduce in Supershrimp tanks are the Supershrimp macroalgae, which is an unknown species of Chaetomorpha adapted to very low salinity (not the Chaetomorpha for reef tanks sold in stores and online) and the very mysterious (it simply appeared one day in one of our Supershrimp tanks) Supershrimp mossball (which is NOT a marimo ball, more on that in another article).