Discovered Koi in Abandoned Pond

[Nicole8293]

Good Morning!

I moved into my grandmothers old home this past winter. The house has been minimally touched for the past 7 years so I was surprised when we discovered fish still in the koi pond. From my current count there are at least 15 koi still in the pond. When I was a child we use to feed the fish and there was a waterfall/filter system. From what I can tell, the pond hasn’t been maintained or had any filtration in over 7 years. I found some old koi food and tossed it in and none of the fish ate it so these are clearly “feral koi” They seem to be doing well and definitely enjoy the cover of the leaves floating in the water.

I personally have kept and currently keep planted freshwater fish tanks and saltwater live reef and fish tanks so I have a pretty good idea on aquatic life care.

I did find some old sketches of the pond’s dimensions so here are a few facts:

Located in Massachusetts, USA
Pond was established in 1997 and has been filled with water and fish ever since.
Shallow spot is slightly over 2ft
Deepest point is 3ft 8inches

Now for the questions. Should I actually do anything for the pond? I’d like to clean it up a bit, replace the floating leaves with floating plants. If possible i’d like to restart the waterfall for water circulation, but i’m unsure if that’s necessary or even possible. Should I even bother feeding the fish? There is a super thick algae layer on the pond liner and they seem to be nibbling on the leaves. Any advice or answers would be appreciated!

 

[MitchM]

Welcome Nicole!
What is the water volume of the pond?
What are the sizes of the koi?
Do not feed the fish any more, there is plenty of natural food for them to eat.
Please post some pictures.
Given the age and history, I would be concerned that any major water disturbance could release some H2S that would be harmful to the fish.
Test the water (KH, GH, PH and time PH was measured, water temperature, nitrates, for now) and try to determine how much detritus has built up on the bottom, then you can carefully proceed with further cleanup.
KH adjustment will probably be needed before you do anything.

 

[j.w]

@Nicole8293
How neat the fish seem to be doing well w/no help. I will leave the koi help to others as I only have goldfish.

 

[addy1]

Wow nice find and neat they have survived.

Welcome to our forum! Post some pictures when you can.

 

[MitchM]

Another question - How has evaporated water been replaced over the years?

 

[Bluerooster]

There ya go. Chalk one up for mother nature. +1 on checking water quality. I'd do it at different levels.
Question asked above is on my mind as well, how was the evaporation taken care of over the years?

I guess, that being in Mass. there is regular rainfall, (weekly) of at least 1/10" to keep it topped up naturally?

A few pics would be nice too.