Help, my tank has a what appears to be detritus worm.

[willlll]

General Overview

So my tank has been up for about 1/4 of a year now and i've had no issues until recently when i found a massive, chunky worm with a black streak and black dots on its back, that likes the dark (I found it in the morning) and has what i believe is wormlings on the underside of it. It doesn't have arrow head so not a planaria and moves like how worms would but moving apart of itself forwards than moving the backwards and so on.
Possibility of Root Cause

I believe it may have came from a plant delivery i got a month ago with vallisneria and hornwort, in which they may have hitch-hiked, and before anyone asks I live in Australia, NSW. I'm a fairly new fish keeper as i only have had another tank prior and my current tank dimensions are 60cm(long) X 30cm(wide) X 36cm(high). The overall shape is more of a rain droplet and a detail is that it moves the smallest part of it foward than pulls itself.

Details

I have seen the large specimen in which i have already gotten rid of eat a pest snail and I believe during my process of getting rid of it released its wormling and i can see them on the glass occasionally but most of the time they are at the sides of the tanks. I'm very concerned for my inhabitants which are 5 corydoras (albino) and a large reproducing colony of shrimp, there are also some copepods. My tank is planted decently and i have only been doing water top offs as I am still attending school.

I will try to get photos when i can but don't expect it too quickly.

 

[Fishfur]

General Overview

So my tank has been up for about 1/4 of a year now and i've had no issues until recently when i found a massive, chunky worm with a black streak and black dots on its back, that likes the dark (I found it in the morning) and has what i believe is wormlings on the underside of it. It doesn't have arrow head so not a planaria and moves like how worms would but moving apart of itself forwards than moving the backwards and so on.
Possibility of Root Cause

I believe it may have came from a plant delivery i got a month ago with vallisneria and hornwort, in which they may have hitch-hiked, and before anyone asks I live in Australia, NSW. I'm a fairly new fish keeper as i only have had another tank prior and my current tank dimensions are 60cm(long) X 30cm(wide) X 36cm(high). The overall shape is more of a rain droplet and a detail is that it moves the smallest part of it foward than pulls itself.

Details

I have seen the large specimen in which i have already gotten rid of eat a pest snail and I believe during my process of getting rid of it released its wormling and i can see them on the glass occasionally but most of the time they are at the sides of the tanks. I'm very concerned for my inhabitants which are 5 corydoras (albino) and a large reproducing colony of shrimp, there are also some copepods. My tank is planted decently and i have only been doing water top offs as I am still attending school.

I will try to get photos when i can but don't expect it too quickly.

The way it moved is the key - it’s a leech. They lay eggs and are quite difficult to eradicate once established, because the eggs are incredibly tough & resilient.

So whatever it was that you saw, it wouldn’t have been a newborn leech, though the term wormling is kind of cute.

The smaller ones you’re seeing will have hatched from eggs.

Around 75% of all the species are parasitic - feeding on blood.

The rest are either detritivores or carnivores. The detritivores feed on just about anything that’s dead and are harmless to other aquatic life.

The carnivorous ones mostly feed on small invertebrates, including snails.

Quarantine isn’t just for new fish. It’s a very good idea for new plants as well - unless of course they are tissue cultured.

 

[tam]

A trap is maybe your best option - you don't mention size but you can get planaria traps that would possibly work if it's similar sized. Otherwise you could try a diy one with a plastic bottle - you want holes small enough the shrimps can't get in.