Hi

I am new in having tetras. I recently acquired 6 Penguin Tetras. Is it a normal characteristic that they swim against the current of an internal filter? as they seem to be fine and eat and swim normally.

Thanks

Most tetras, including Thayeria obliqua love some current and hang out together in the filter outflow. Penguins have an unusual characteristic and swim at a 45 degree angle due to low buoyancy of their tails. In the wild, these fish lie just below the surface among dense vegetation and feed on insects falling on the surface. Make sure that the tank is well covered cause they are also great jumpers.

Thanks for your reply. Its very nice the way they swim fascinating :). I was informed from their previous owner as he lost some that jumped out of the tank. They should enjoy the java ferns around them.

Hi, I m planning to set up a tank with tetras. I know that tetras prefer a pH of 5.5 to 7, and this should be fine since presently the pH in my tank is low. To set up a tank for tetras I need alot of plants. My questions is that if I add alot of plants, will they lower drastically my pH level? At the moment I only have  Water wisteria plants  and 3 small pieces of lava rock and the the pH falls from 7 to 6 in 10 days or less! 

Also,  what's the ideal number of tetras for a 120 ltr tank? I have 2 algea eaters, 2 bronze catfish, 8 adult mollies and 10 molly fry (2months). I m planning to remove the mollies once I ll buy the tetras. 

thanks

Hi Ribbon tail,

      well increasing PH is much easier than decreasing it and you should not have any issues there just keep monitoring to find the perfect balance. One can increase PH easily with crushed corals in the filter or else via PH buffers which you can buy from the site or LFS 

i have a 150 ltr tank in which i have 8 big pieces of rocks (nahseb xi gebel tal-gagazza)......been in my tanks for over 15 years, and in this tank the pH is always stable at 7. Could it be that the pH level is fine due to these rocks? I refill this tank with the same water as the others, but it's the only tank in which pH is stable. In the others i need to make partial water changes every week. and it's not a question of amount of fish, cos the 150 ltr tank is quite over-stocked, while the one which has low pH has less than 20 livebearers.

I ll try to place one of the rocks in the other tank and check whether pH will fall drastically or not. Just want to ask whether pH level can keep stable due to such rocks. thanks

yes the rocks do affect the PH in fact some place limestone based rocks as decoration just to stabilize the PH.