GardenBanter.co.uk - weird breeding onset....fish and plant...

HI folks, got a new one, and I figured Idd see what the collective wisdom
is....

I've been keeping tanks for over 30 years, and have more or less etteld on a
single large community tank - 125, well panted, stocked with genereic
community type fish.

For some reason, about 2 weeks ago, *everyth9ng* went into major breeding
mode - Now, I expect the platies, swordtail, guppies, etc to pretty be
constant breeders (provides "chase food' for the others, if nothing else.
But also, the gouramis, tiger barbs, zebra danios, and coryadoris are all
showing signs of breeding (large egg masses, courting behavior, nesting,
etc.). Not only that, but the plants sudenly went into breed mode too. Now,
I can't say as I bother to do anything special for the plants. I've got a
few different varieties of "sword" type plants, some java fern, and a
fairly random assortment of bulbs that I've come across over time. All of
the sword type plants have sent shoots to the top, and at least 3 of them
have flowers. The rest just have leaves on the surface now.

I was prett cool with all of this activity - the tank has been pretty stable
fro a few years now, and there hasn't been any change that I've made
recently. I do a 50% water change every week (we have good well water, so I
don't bother to treat). I occasionally (like every toher week) give a dose
of lef zone fertilizer, but other than normal flake food, thats about it.
Nothing special equipment wise - undergravel filters, eheim canister, the
hood has a set of harware store type grow lights in it.

Any thought as to what could have triggered this sudden change? i don't know
if its cause or effect (I tend to think effect because it just happened),
but the nitrate levels have spiked up during the last week, they've held
steady at about 20 )for the past 2-3 years), but when I tested today they
were up in the 50-60 range. there are a lot of baby fish hanging out inthe
tank now - theres probably an additional 60 or so fry hanging about that
haven't been eaten yet (this is realy a lot for my tank - i can usually hunt
and find one or two, but a simple glance shows the swarms...). I'm guessing
(and hoping) that the spike is a result of tha dditional fish waste being
produced by al those babies.....

shouldn't the plants be sucking it all up though? (the nitrate) I though tht
they liked it.....

Oh well, thanks for reading, and any feedback will be appreciated....
thansk
-_JD