So I had just gotten a new 2.5 gallon tank for my betta. I wanted to put a filter in there to keep the water clean and circulate the water. I first bought the Whisper filter for tanks up to 3 gallons and was very disappointed (very loud and it didn't actually filter the water at all), so I ordered this one on Amazon. So far it is working great. It is actually very quiet. I have the tank sitting right next to my bed, so having a quiet filter is a must. I can barely hear it, but the sound it makes is a constant, soft, bubbly sound, so it's great for sleeping to anyway. Since it is supposed to work for tanks up to 6 gallons, it is a bit powerful in my little tank, so I put a small strip of pantyhose around part of the intake to slow down the flow a little bit. I see there are a lot of people saying their fish got sucked into it. To be honest I doubt that is the case most of the time. What probably happened is the fish died on its own, and since the filter sucks up any floating debris, the dead fish will get sucked into it, making it appear as though the filter was responsible. If you're still worried about it though, you can do what I did and cover the intake partially with pantyhose (don't completely cover the intake or it won't work; I have about half of it covered). Overall, this filter was the best one I can find for a 2.5 gallon tank. It is smaller than any other filter I found, it keeps the water clean and aerated, it's quiet, and the replacement cartridges are pretty cheap. The only thing about it is I couldn't use the attachment clip for it because I wasn't able to put the lid on with it that far out of the water, so I basically just have it standing up in the tank. It still works though, although you probably want to make sure that the filter isn't completely submerged. I'd definitely recommend this for betta owners! Just an update: it's been a couple of months. I went ahead and took off the strip of pantyhose. I have a fake plant in front of the filter so as to break up the flow a little bit. The filter is still working and it's not too powerful for my betta. He actually likes to rest on that plant right in front of the filter, doesn't seem bothered by it one bit. Like I said before, I'm not worried about him "getting sucked in and killed". I think those fish either died first, then the filter sucked them in. Either that or maybe these people had the fish in too small aquariums. In my little 2.5 gallon though, it's working great -- still quiet, still cleaning, and not too powerful. Still recommend it! Second update: So my betta died after living with me for about two and a half years :( He was not sucked into the the filter though; he died on the opposite side of the tank and was there until I took him out. I ended up getting another betta after a couple weeks, and I'm using the same filter. While my previous betta didn't seem to mind it at all, this one did not seem as well able to handle the current (he has much longer fins than the other one did, so that's probably why), so I covered most of the intake with pantyhose again and he is now doing great.
