Brackish Mangrove Tank

6/24/2008 – Time to start documenting another biome build I’ve begun. I’ve been given access to an approx. 50 gallon acrylic tank at work. My plan is to set it up as a brackish water environment with mainly Southeast Asian inhabitants. The tank needed some repairs (new pump and air hoses – done) and needs a good cleaning. Once that’s done, I’ll move it to it’s semi-permanent home and get the heavy stuff – substrate and water – added.

System specs:

  • The tank (w/o filtration area) is 36″ x 18″ x 18″ – approx. 50 gallons.
  • Water targets – specific gravity = 1.010, pH = 8, temp = 75F
  • Lighting – mainly natural light. I plan on siting it in the little greenhouse alcove where it can share space with some orchids and carnivorous plants. Using the sun to light a tank is usually frowned on – the water can get overheated quickly. I want to have mangroves growing out through the top (no lid) which means it’ll be difficult to light with bulbs and the tank has an integrated chiller – keeping the water cool won’t be impossible.
  • Filtration – the tank has an integrated filter. It’s a combo mechanical (filter pad)/biological (bio-balls) system – with air supplied to the biological area. I’m going to keep stocking levels low – we’ll see how things work.

Click through for additional notes.

I’ve ebayed 2 mangrove seedlings and 4 Cryptocoryne ciliata; I have a bunch of Java moss and Java fern I’ll add as well. The plan – subject to change w/o notice – is to get things set up, plant the tank and let it sit and stabilize for a bit. As it settles down, I’ll add some grass shrimp netted locally, then – later – an Archerfish (Toxotes sp.). Down the road, I’d like to add a couple Mangrove killies (Rivulus marmoratus) – they’re not from SE Asia, but they are self-fertilizing hermaphrodites – how cool is that?

6/28/08 – Time to cycle the system. The tank is sitting in its new home and is pretty well set up and planted. I let the tank run – empty except for water – to make sure everything was still sound – it was.

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Emptied it out and off it went into the greenhouse alcove. I’m trying a bit of an experiment with substrate. I’ve had very good luck with this aquatic plant soil in my whiskey-barrel lotus garden; I thought I’d try it in this tank and see how it did indoors (but in a high light situation).

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There, I fixed that for you.

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The 18l bag gave me an approx. 1 1/2 inch layer on the bottom. Once the soil was well wetted, I planted the 4 Crypt. ciliata. To cover the soil and buffer the water, I added a bag of aragonite/crushed coral/something.

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One of the folks I work with had an old hunk of brain coral skeleton which he contributed to the cause – in it went along with a piece of driftwood (with some java fern attached). Then the mangrove seedlings got planted – three of ‘em – all at different depths. I want to see if depth makes a big difference – I’m hedging my bets. Last things in were 3 male guppies to supply inputs that will kick off the nitrogen cycle. More pix in a couple days…

6/30/08 – I took some pictures this morning as promised. Not much to report – I continue to fiddle with the top end of the filter to get an even distribution of water through the bio-balls.

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7/17/08 -the Toxotai swept through the area and left behind one of their number – a Toxotes chatareus.

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To say he’s thin would be an understatement. I’m plying him with bloodworms (thawed frozen) and crickets (live), trying to feed small amounts frequently to minimize the demands on his digestive system. He’s eating; the unanswered question is whether the stress of shipping/starvation/etc. has pushed things to the point of no return.

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Not a great picture, but one that should make you think about the problems faced by a fish that spits at bugs above the water. That these guys can deal with refraction is just amazing.

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The crypts are doing the expected – melting. Folks who aren’t familiar with the phenomenon – cryptocorynes are famous for turning to mush when water conditions change (pretty much inevitable when you buy ‘em). They usually recover; the C. ciliata are (knock wood) coming back quickly.

7/18/08 – the archerfish stress question was answered today. He was Tango Uniform when I checked on him first thing. The LFS is going to talk to the distributor and try to get a better specimen. (LFS in aquarium context = Local Fish Store; LFS in carnivorous plant context = Long Fiber Sphagnum).

8/9/08 – The new archerfish has been resident for over a week – thriving. He’s bigger than the last one and arrived in great shape. He’s voracious – crickets, guppies – if it moves, he’s on it. I was thinking about putting some bumblebee gobies in the tank; after seeing him in action, that idea is on ice. The little gobies would end up as expensive feeder fish. There has been a bit of an algae bloom – not unexpected – I have some snailsĀ  (Neritina reclivata) on the way to do some grazing.

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12/5/08 – Just a quick update on system status. All’s well (knock wood) in our little slice of southeast Asia. The nerites are doing a good job on the algae – there is some hair algae that I prune out every once in a while that they don’t seem to like and some red algae (relatively complex) that I wish would grow a little more. The archerfish continues to eat everything I throw at him, as long as it’s alive. I’ve had no luck transitioning him to prepared foods; he wants motion.

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6/9/09 – the tank is coming up on it’s first birthday! Changes since my last update:

  • The hair algae decided that it really liked conditions in the tank and took off growing like mad. I got tired of removing it myself and introduced a green scat (Scatophagus argus). The scat cleaned out all the hair algae and wants more – I seemed to have lucked into a vegan individual.
  • The mangrove seedlings declined and died over the winter. I think I may have pushed the envelope as regards planting depth. I bought another batch off eBay and planted 2 much higher in the tank. They’re sending out new roots; my fingers are crossed.
  • All but one of the crypts melted into nothingness – I’m thinking good thoughts at the survivor, but am not sure what else I can do to encourage it.
  • The archerfish keeps growing – big and healthy – huzzah!
  • I swapped out the filter pad/mesh arrangement I had been using on the top of the trickle filter for a piece of Poret foam left over from anothe project. It’s working nicely.

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