Correct upkeep of hexagon pond

[ThatBloke]

good morning People

First thanks for the use of this forum

I have an issue with one of those raised ponds and seeking advice from you.
Personally I don't have an dealings with it ( my wife does) but this morning i had to help free a fish entangled among plants and that what i think is algae...thick green stuff. It was in his mouth and gills. pair of scissors and steady handy was needed
The pond water is muddy and far too much green stuff. Im no expert but this can't be right and im surprised the fish have survived the past 5 years.

Can any of you give me some advise how to maintain this properly ie correct pump, correct plantlife and anything else to keep the pond clean and habitable?

Image is similar and the dimensions are 23" x 39.5" . So id guess 400 litres (88 gallons) of water

Many thanks

 

[j.w]

@ThatBloke
The pond is small enough for you to reach in there using perhaps a bottle brush which you can twirl around and drag the stringy algae out. On bigger ponds one would use a clean toilet brush but w/yours it would destroy everything in it's path. Some use Hydrogen Peroxide in the water but not sure it would be used in this case or not and you would still have to drag out the dead algae.

 

[JRS]

Welcome! How many fish are in the pond? Gravel? Do you have any detailed specs on the equipment included? I might treat it more as an aquarium, doing regular partial water changes using a gravel cleaner to siphon accumulated crud off the bottom. Rinsing the filter in a bucket of water from the pond -removes accumulated crud, maintains proper water flow, and preserves beneficial bacteria on the filter.