Platy Aggression

apologies if this topic has be discussed before but I couldn't seem to find a suitable thread.

I have a 200L tank. semi planted.

stock
2 goldfish (oranda)
8 danios
6 platies 3/3 male/female ratio

I have noticed for the last two days that 2 male platies have been harassing my goldfish. I mean there's a clear size difference yet the two male platies have been chasing and nipping the two goldfish and not allowing them to get any rest. they don't tend to chase the danios or other platies, just the gold fish.

is this behaviour normal? should I be worried. if so what should I do.

Video of the fish chasing the goldfish?

They could be trying to breed with the goldfish (it won't happen tho) or they are bullying the goldfish.

As a general rule for keeping common livebearers like platies in community tanks, try to only have one sex (either males or females). I prefer females because they are less stressful to the other fish in the tank and don't constantly try to breed with everything.

Silly question. How do I attach video?

It isn't a good mix, as in time the goldfish will turn the tables and eat their tankmates. For now, the platys may have discovered goldfish body slime, a delicacy for many other fish. If they are a very deformed type of fancy goldfish, they are sitting ducks for that.
Or, the platys are singing "I like big butts and I cannot lie" as they try to mate with the goldies.

We get some twisted fish behaviour in tanks. I disagree with Colin about single sex groups of platys - I've always liked keeping trios (1 male) because I like to see platys being platys.

What is the solution in this case? Is this behaviour harmful to the fish?

My solution would be
a) someone has to go. It's goldfish or other fish, since the goldies produce so much waste and get rather large. If the other fish are nibbling on the goldies, it can be harmful;
b) a second tank for the goldies, but remembering how large they can grow and how long their lifespan should be (30 years) - a large tank of 25 gallons/100 L per goldfish.

You can see my bias though - I dislike fancy goldfish and like platys and danios.

Second fish tank is out of the question. It got some convincing the wife for this fish tank alone.

I’ve rang a few pet stores and they don’t take fish from the public. So I’m in a bit of a dilemma. I don’t know anyone that would be willing to take fish on.

As you are in the UK you could try advertising on https://www.aquarist-classifieds.co.uk

I managed to find someone who has an outdoor pond which has no fish in. My goldfish have a new home.

I suppose a follow up question would now be what fish can I keep with my zebra danios and platies. Any suggestions?

badbrownbear said:

BadBrownBear on Instagram

4 likes, 0 comments - badbrownbear on February 12, 2022

www.instagram.com

Click to expand...

That video showed the platies pecking at the goldfish and eating it.

The goldfish was also having a few issues swimming down and that would probably be caused by air in its intestine, which in turn is caused by lots of dry food.

--------------------

badbrownbear said:

I suppose a follow up question would now be what fish can I keep with my zebra danios and platies. Any suggestions?

Click to expand...

What is the water temperature?
Danios and platies do well in water with a temperature around 18-26C. They can take higher and lower temps but the danios tend to become egg bound if kept in warm (24C+) water all the time.

What are the tank dimensions (length x width x height)?

What is the GH (general hardness), KH (carbonate hardness) and pH of your water supply?
This information can usually be obtained from your water supply company's website or by telephoning them. If they can't help you, take a glass full of tap water to the local pet shop and get them to test it for you. Write the results down (in numbers) when they do the tests. And ask them what the results are in (eg: ppm, dGH, or something else).

I’m assuming pecking and eating another fish isn’t good news is it?

I have noticed a few swimming issues with one particular gold fish. I have tried varying the diet where possible. Ranging from pellets,flakes,bloodworms, broccoli and peas. The other seemed fine swimming wise.

The tank dimensions are 100cm x 40cm x 50cm. 200L

The temp is around 18-21

Water parameters for ammonia and nitrites at 0.0ppm nitrates are around 20/30 ppm

The water hardness is generally soft

badbrownbear said:

I’m assuming pecking and eating another fish isn’t good news is it?

Click to expand...

Nope, it's bad news when fish start eating other fish, especially when they are alive.

badbrownbear said:

I have noticed a few swimming issues with one particular gold fish. I have tried varying the diet where possible. Ranging from pellets, flakes, bloodworms, broccoli and peas. The other seemed fine swimming wise.

Click to expand...

If it's a short body fish with a double tail, then it's caused by having their body shorter than it should be and their guts and organs get squished up together. This is from the breeders. Basically they ingest air and it is harder for the air to go through their digestive tract and they can float around.

The best thing for these types of fish is to minimise the dry food and feed mainly plant based foods and frozen or live foods so they don't take in air when feeding.

The image in post #13 is the water quality report. Is there something else which gives hardness?

The calcium level isn't the same as hardness but it is a good indicator, and yes that's soft water. The actual hardness level will confirm that.