Amazon frogbit on the decline

[PPulcher]

I got some amazon frogbit (Limnobium laevigatum) at a club auction back in October. I put portions into a tanks with just over 2 watts of T8 lighting (basically, I have 5, 5.5 gallon tanks on a rack with a T8 shoplight over it), and some in a 15 gallon tank with about 2.6 wpg of T12 lighting. The 5.5s are bare bottom with large wads of najas (guppy grass). The 15 has a couple of big anubias and a little najas. I don't add any fertilizers or anything, but the tanks are pretty heavily fed.

The frogbit did well at first, sending out new plantlets and roots. The plants now seem to be on the decline however. The roots have pretty much gone, and much of the original plant mass is gone. I can't normally measure any nitrates in these tanks (I guess the najas does a good job) so I suspect this may be the problem. Any other guesses?

[grumpystiltskin]

I believe this plant requires a higher light,and good fertilization.
I had it in a low light tank and it did the same thing, slowly died off, but when i used it in a high light tank( 3wpg) it flourished, and grw quite quickly .

[PPulcher]

Ah, I see. I figured it was close enough to the lights to make up for ~.5 watts or so. I'm not running any tanks with that much light right now so I guess it will end up as compost :mad:

[Bcanoe]

I'd lean more to nutrients. I run this one in all of my low light planted tanks to suck up excess nutrients. All tanks are 1.3 to 1.4 watts/gal of normal output t12s and it grows great. Light are just above the cover glass and i toss it out on a regular basis.

The only tank it doesn't do so well in is my 5gal bare bottom never used never fed quarantine tank, but even in there it's gaining slightly. (The java fern in there is loosing ).
Even in my lightly stocked hardly fed low nutrient 10 gal shrimp tank it does well corralled under a screw in 10watt spiral.
Did it ever put out any very long roots when it did well.

Cheers Bill

[PPulcher]

Perhaps I'll try a little KNO3 and see if that perks things up. I have a feeling that the najas and the frogbit don't get along due to competition.

[Bcanoe]

[quote=PP I have a feeling that the najas and the frogbit don't get along due to competition.[/quote]

That would be my guess also.
Cheers
Bill

[PPulcher]

Come to think of it, even the errant bits of duckweed that make it into these tanks don't explode like they do elsewhere. This might be worth investigating as a way to get rid of the stuff when it becomes a problem.

[ChrissyFishy]

I thought the topic meant it was on the decline in the wild :Embarassing: :laugh: .

[PPulcher]

Okay, so I removed most of the najas from the tank, and I've been adding some nitrate, potassium and traces to the tank this week in the style of PMDD. I haven't had much time to measure the nitrate in the tank, but I'll do that this weekend before water change time. I gave a plantlet to DaFishMan to see if he could nurse it back to health!

[CACAdmin]

When I bought frogbit for my pond at one time, I was informed that it preferred very little water movement. Could this possibly be a contributing factor in its decline in your tanks?

[PPulcher]

Possibly... I have a box filter in the tank with the remainders of it set to what I would call low/medium flow of air.

I'm really thinking it was competition with the najas. The fugitive bits of duckweed that one sometimes gets hardly even grow well in tanks that I keep najas in!

[Melody]

Considering how much some people hate it (my snails beg to differ), its worth a shot to get try to get rid of it with Najas. If anyone tries it, please post. :smile: