Brackish Tank Idea.

eschaton

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Hey all.

I currently have two 20 gallon freshwater. The fish were originally all meant for the same tank, but I overbought when I first got into the hobby, and needed to buy an emergency tank to split up the ranks.

Probably within a few months, I'm going to get a much larger freshwater tank (40ish gallons) and a nano (for my cherry shrimp and DAFs mainly) and split the current tank inhabitants between them. Which would leave me with two 20 gallons to do interesting things with. Thus my brackish idea.

I mostly want brackish because I want a crab. From what I gather Red Claw or Fiddler would be best, though I realize in both cases, I'd need to come up with some sort of land setup which would really limit the gallons to work with. Assuming I use rock piles instead of sand, I could probably still have around 15 gallons worth though. The only brackish fish that realy interest me are teeny ones like bumblebee gobies and "freshwater" pipefish. I'd also probably be interested in learning how to condition my guppies for a lightly brackish tank. Also moving over my nerites, some malaysian trumpets, either rehoming or getting new shrimp, etc.

I'd really like mangroves in there. I've read about them and they seem a fascinating addition. I'm a bit concerned how they work practically in a brackish aquaria though. I have plant lights right now which I'm sure would be a help, but they rest on the tank lid. I guess you can't keep a lid on the tank if you have mangroves? What stops the crabs from climbing the trees and falling out of the tank?

Anyway, this will probably wait for a month or two, but I could use the advice of you guys in the planning process.
 
Hello and welcome to the brackish branch of the hobby!

Fiddlers are probably the safest crabs to get because they don't normally eat fish. They basically feed on algae and protozoans in mud, and spend most of the time sifting mud or sand if they have some. Red-claw crabs are more omnivores and will eat anything -- including fish -- they can catch. If you're planning to keep gobies or other small fish, then red-claws are a risk.

Nerites and trumpet snails do well in brackish, as will certain shrimps (Amano shrimps do fine in slightly brackish, for example). Guppies are easily adapted to 1.005 across 30-60 minutes of the "drip" method (put them in a bucket and dribble in salty water slowly). Actually, use any method you like. I tend to simply put fish in a half-filled bucket and then add a litre of salty water every 10 minutes. Mix and match to suit your needs and what equipment you have. Guppies can be taken up to full marine, but that takes much more time, several weeks, ideally.

Mangroves are possible but yes, they need space above the tank. They also need good lighting. One thing ignored is this: once a mangrove propagule (the "pod") has sprouted roots and leaves, it cannot easily be adjusted to a different salinity. Only ever buy propagules that are unsprouted. These can be stuck in the aquarium in a variety of ways. If you stick them straight in the sand, you won't get "prop roots" which are the sideways, arching roots that make them look cool. Instead, float or fix them somehow so they are 1/2 in the water and 1/2 out (replacement heater attachment suction cups are great for this). This way, the bottom half will sprout prop roots. Keep winching the plant up every few weeks to encourage more prop roots, and when you're happy, then plant in the sand.

Yes, the crabs will climb the mangroves, and yes, they will escape.

Hope that helps,

Neale
 
Thanks Neale,

Here's an alternate plan I thought of to include mangroves as well as fiddler crabs: buying a 30 Gallon tall (same base as my current 20 gallon highs), and fill halfway with water. All the old tank equipment would fit this tank (though I'd need extentions on the filter intake), and there would be enough space for the mangroves to grow about a foot above the water before pruning.

Biggest negative I could see here is that it would be really hard to work out some land for the fiddlers without taking it down from an effective 15 gallon to a 8 gallon or less. The mangroves would fix the nitrates of course (the whole reason I find it such a elegant solution), but that's still not a lot of water space to work with.

I'm trying to figure out if I could work some sort of rock wall up the back side of the tank. maybe integrate the filter flow into it so that I could have a mini-waterfall (since it will essentially be that anyway, it might as well look nice), but it wouldn't look very mangrove-like. Do fiddlers need sand above the water level, or will any old thing (say, climbing some mangrove saplings) do the trick?
 

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