Molly fish are not acting right

[u/holybaconbatman13]

Hello! I have 4 black mollies, and up until a few days ago, they were very active and healthy looking. I performed a partial water change and tank clean like I do every week (gravel vacuum, swished the tank filter in the old tank water) In the last few days, they've gotten way more lethargic, laying on the bottom of the tank, and they look so skinny. I plan on doing another partial water change today to clean up everything and see if it helps? The water looks so cloudy which it's not normally like that. I tested the water and it's not any different than it's always been, the pH and alkalinity are very low but they have always been like that, since I got the tank. TIA!

[u/wetmyplantiez]

Yes, we do need the actual number of your water parameter. Saying “not any different than it’s always been” means nothing to us. In general live bearers prefer harder water but tbh, you might have other issues going besides low water PH.

[u/mathucias_]

Maybe the tank is too small, that's why it gets cloudy quickly and why they're not active, they maybe does not have enough space to swim freely

[u/RainyDayBrightNight]

How old is the tank?

What size is the tank?

Have you done any maintenance lately such as cleaning the filter or changing/cleaning the substrate?

What’s the ammonia, nitrite and nitrate in ppm?

[u/holybaconbatman13 → u/RainyDayBrightNight]

The tank is about 6 months old, 10 gallon. I did a partial water change about 4 days ago, vacuumed the gravel and rinsed the filter in the old water. I don't have the ppm info in front of me, I'll check it again when I get home

[u/holybaconbatman13 → u/RainyDayBrightNight]

I don't have a strip that tests ammonia but the pH is 5.5, the alkalinity is 700ish and nitrate/nitrite is 0.

[u/RainyDayBrightNight → u/holybaconbatman13]

That’s bizarre 😅

Very high KH, very low pH, weird. Definitely test your tap water asap to see what it says.

Fish pee ammonia instead of urea, and ammonia is highly toxic. If the tank’s cycle crashes, the ammonia can build up and burn or poison the fish. Having ammonia test strips is similar to having a carbon monoxide detector in your house.

The tank is definitely too small for mollys, which is probably why bacterial blooms take hold so easily.

Definitely test ammonia asap. The test strips are sold separately due to using a different chemical reaction

[u/holybaconbatman13 → u/RainyDayBrightNight]

I appreciate your feedback: I got some supplies, tested the ammonia and it was very high. I added an ammonia treatment, and also something for the low pH. I added some aquarium salt as well and did a partial water change. They are so much more active now, so I'm hoping I got out ahead of it.

[u/RainyDayBrightNight → u/holybaconbatman13]

Low pH is probably caused by ammonia then, seeing as ammonia is acidic.

Do a 50% water change to remove the ammonia completely. Ammonia treatments just bind to the ammonia, they don’t remove them, meaning you then have to do partial water changes to remove ammonia.

To do a 50% water change; 1. Use a gravel vacuum to suck 50% of the water from the gravel/sand into a bucket, removing the gunk from the gravel/sand with the dirty water 2. Tip the dirty water down the loo, or use it to water your plants 3. Refill the bucket with tap water of a similar temperature to your tank water 4. Add a proportional amount of water conditioner 5. Swish it around and leave to stand for 3-5 minutes 6. Use the conditioned water to refill the tank

Aquarium salt is a great idea, it decreases the total toxicity of ammonia. Be careful not to leave salt in the tank water for more than two weeks though, or it can cause health issues.

You’ll need to do a fish-in cycle, though it’ll be very prone to crashing again, because the tank is too small for the bioload of mollys.

Cycling is the process of growing nitrifying bacteria in the filter media. These nitrifying bacteria eat ammonia, keeping the water clean. They take an average of 3-6 weeks to colonise a new tank. In a healthy filtered tank, roughly 80% of the nitrifying bacteria will be in the filter media.

To do a fish-in cycle;

Test the water for ammonia and nitrite every day for a month. Every time ammonia or nitrite reaches 0.5ppm, do a 50% water change and test again.

Most likely, there’ll be an ammonia spike at the start, then a nitrite spike at around week 2-3. The nitrite spike is often what kills fish.

By the end of a month of testing and water changes, the nitrifying bacteria should’ve grown colonies in the filter media. These nitrifying bacteria carry out this process;

Ammonia (toxic fish waste) -> nitrite (moderately toxic) -> nitrate (harmless plant food)

Nitrate should be kept below 20ppm to avoid algae issues.

The most commonly recommended test kit for beginners is the API liquid test kit.

Once the tank is fully cycled, you’ll only need to do a 20-30% water change once a week. To do a 20% water change; 1. Use a gravel vacuum to suck 20% of the water from the gravel/sand into a bucket, removing the gunk from the gravel/sand with the dirty water 2. Tip the dirty water down the loo, or use it to water your plants 3. Refill the bucket with tap water of a similar temperature to your tank water 4. Add a proportional amount of water conditioner 5. Swish it around and leave to stand for 3-5 minutes 6. Use the conditioned water to refill the tank

[u/KingofAnti-Social]

Mollies need hard, alkaline water. They don’t survive in softer water. These are bound to die sooner or later.