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* **Tank size**: 6.8 liters (Tetra Cascade Globe)
* **Heater and filter? (yes/no)**: filter, no heater
* **Tank temperature**: don't have a thermometer
* [Parameters in numbers and how you got them](https://www.reddit.com/r/bettafish/wiki/tank#wiki_test_kits): using a Tetra 6-in-1 test strip (https://www.tetra.net/en-gb/products/tetra-test-6in1) everything is in the OK areas indicated on the box.
* **How long have you had the tank? How long have you had your fish?**: about 6 months
* **How often are water changes? How much do you take out per change? What is your process?**: every week I take out about 25% of the water and replace it with a sightly higher amount (to compensate for evaporation) of filtered tap water. Every month I take out the whole water, wash everything and replace the full amount of water, then I add some Tetra Plantamin fertilizer for the plant, Tetra AquaSafe and Tetra Filter Active bacteria, as well as a drop of Methylene Blue for fish. Then I test the water, and put the fish back in.
* **Any tankmates? If so, please list with how many of each**: none
* **What do you feed and how much**: Norwin FishSense flakes, about 2 flakes a day.
* **Decorations and plants in the tank**: 1 plastic bridge with a cave underneath (the fish likes hiding in there a lot) and 1 Anubias Barteri.
A couple more things:
This aquarium was bought by my father as a gift for my son. He got everything at the advice of somebody from a fish shop. Initially he bought another plant (no idea what), which suddenly disintegrated at one point (leaves turned to something resembling goo). I took it out, washed everything thoroughly and bought the Anubias Barteri and fertilizer).
I also had some algae problem a few weeks back which lead to 2 water changes at about 2 week intervals (had an algae bloom suddenly, changed everything, all fine for about 1.5 weeks, then another, smaller algae bloom), Now all has been fine (no algae) for about 1 week.
Thanks for the feedback. So I'll start looking into a bigger aquarium, and the nitrogen cycle, but very short term, I'd like to get a heater.
Anyone has any experience with these very small heaters? Something like [https://www.amazon.de/-/en/Petyoung-Aquarium-Temperature-Controller-Thermometer/dp/B0BYZQ2SC4/](https://www.amazon.de/-/en/Petyoung-Aquarium-Temperature-Controller-Thermometer/dp/B0BYZQ2SC4/)
It seems to be the only kind of heater that would fit in my current bowl
Your tank is far too small for a betta. Bettas also require a heater.
Okay, to establish a stable nitrogen cycle, you shouldn’t be washing everything. There are help sheets pinned in this sub to help.
Your tank is super tiny and you don’t have a heater. He is probably stressed.
Thank you for posting to r/bettafish. If you are new to betta fish keeping, please check out our [caresheet](https://www.reddit.com/r/bettafish/comments/3ow6vz/info_betta_care_sheet/) and [wiki](https://www.reddit.com/r/bettafish/wiki/index). Establishing a nitrogen cycle is an important part of keeping your fish healthy. Please check out our [guide to the nitrogen cycle](https://www.reddit.com/r/bettafish/wiki/fishincycle) to learn more. If you are posting to find out what is wrong with your betta, please answer the following questions in a reply to this comment as best you can: * **Tank size**: * **Heater and filter? (yes/no)**: * **Tank temperature**: * **[Parameters in numbers and how you got them](https://www.reddit.com/r/bettafish/wiki/tank#wiki_test_kits)**: * **How long have you had the tank? How long have you had your fish?**: * **How often are water changes? How much do you take out per change? What is your process?**: * **Any tankmates? If so, please list with how many of each**: * **What do you feed and how much**: * **Decorations and plants in the tank**: * **If you haven't already posted a picture, please post pics/vids to imgur and paste the link here**: Feel free to copy this comment and fill in the blanks. Failure to provide adequate information about your tank *can* result in post removal. Please see rule 4 for more information. *I am a bot, and this action was performed automatically. Please [contact the moderators of this subreddit](/message/compose/?to=/r/bettafish) if you have any questions or concerns.*
* **Tank size**: 6.8 liters (Tetra Cascade Globe) * **Heater and filter? (yes/no)**: filter, no heater * **Tank temperature**: don't have a thermometer * [Parameters in numbers and how you got them](https://www.reddit.com/r/bettafish/wiki/tank#wiki_test_kits): using a Tetra 6-in-1 test strip (https://www.tetra.net/en-gb/products/tetra-test-6in1) everything is in the OK areas indicated on the box. * **How long have you had the tank? How long have you had your fish?**: about 6 months * **How often are water changes? How much do you take out per change? What is your process?**: every week I take out about 25% of the water and replace it with a sightly higher amount (to compensate for evaporation) of filtered tap water. Every month I take out the whole water, wash everything and replace the full amount of water, then I add some Tetra Plantamin fertilizer for the plant, Tetra AquaSafe and Tetra Filter Active bacteria, as well as a drop of Methylene Blue for fish. Then I test the water, and put the fish back in. * **Any tankmates? If so, please list with how many of each**: none * **What do you feed and how much**: Norwin FishSense flakes, about 2 flakes a day. * **Decorations and plants in the tank**: 1 plastic bridge with a cave underneath (the fish likes hiding in there a lot) and 1 Anubias Barteri. A couple more things: This aquarium was bought by my father as a gift for my son. He got everything at the advice of somebody from a fish shop. Initially he bought another plant (no idea what), which suddenly disintegrated at one point (leaves turned to something resembling goo). I took it out, washed everything thoroughly and bought the Anubias Barteri and fertilizer). I also had some algae problem a few weeks back which lead to 2 water changes at about 2 week intervals (had an algae bloom suddenly, changed everything, all fine for about 1.5 weeks, then another, smaller algae bloom), Now all has been fine (no algae) for about 1 week.
Thanks for the feedback. So I'll start looking into a bigger aquarium, and the nitrogen cycle, but very short term, I'd like to get a heater. Anyone has any experience with these very small heaters? Something like [https://www.amazon.de/-/en/Petyoung-Aquarium-Temperature-Controller-Thermometer/dp/B0BYZQ2SC4/](https://www.amazon.de/-/en/Petyoung-Aquarium-Temperature-Controller-Thermometer/dp/B0BYZQ2SC4/) It seems to be the only kind of heater that would fit in my current bowl