nmonks wrote: ↑
Fri Oct 26, 2007 2:10 pm
It's quite a good article, but there are several errors, or at least assertions I'd take issue with. Starting from the top:
-- At below SG 1.005, there's a huge variety of plants that are viable. If you're building something for, say, knight gobies, BBGs or mollies, there's absolutely no reason not to keep plants. We've discussed this elsewhere so I shan't bother repeating too much here. But basically anything that does well in hard/alkaline water is worth a shot.
-- The value of measuring pH is one of the biggest misunderstandings in the hobby. Brackish water fish don't want some specific pH; they want a certain level of carbonate hardness, and that carbonate hardness will cause a certain pH. So rather than fussing over pH, concentrate on hardness. Too many people turn to pH-up and pH-down buffers instead of concentrating on chemical filtration, i.e., crushed coral in the filter to raise the KH (and thus the pH).
-- Brackish water fish absolutely DO NOT need to be raised to marine salinity over 3-4 years! You can add your scats and monos to a marine aquarium when they're mere fingerlings. Couldn't matter less. Very few brackish water fish are catadromous or anadromous in the same way as, say, eels or salmon respectively. Normally they are fish that specialise in brackish water habitats, and spend their entire lives moving up and down the salinity gradient. Yes, Terapon jarbua
babies are normally found in fully marine environments, but that doesn't mean they don't tolerate freshwater for long periods; and conversely, while Terapon jarbua
adults are usually found in rivers, that doesn't mean they don't go into the sea some of the time. Likewise for scats, monos, Colombian sharks, etc.
So anyway, this whole section is wrong. What matters when discussing salinity is not the fish, but the filter. You can take mollies or scats and transfer them directly from saltwater to marine, or vice versa, and they'll adapt. It's not nice, maybe, but they'll live. Do the same to your filter, and you'll kill the bacteria. In real terms, adjustments in salinity need to be made gradually (perhaps a couple of "points" on the SG scale, e.g., 1.004 to 1.006) every week or two. The filter bacteria will adjust, and by taking regular nitrite measurements you can keep tabs on things, going more slowly if you need to.
-- This section is a wee bit optimistic in my opinion. Keeping mollies in a 10 gallon tank for example isn't really a good idea, given sailfin mollies regularly top 10 cm in length and can in the females of at least one species reach up to 18 cm. Mixing knight gobies with bumblebee gobies is sort of like mixing knight gobies with brine shrimp -- the shrimps will live fine right up to the point where the knight gobies eat them. And the knight gobies will be equally happy to eat your BBGs! Similarly, mixing mudskippers with crabs isn't a brilliant idea. Mudskippers will eat small crabs, and big crabs will eat small mudskippers. They're best kept in their own tanks.
-- I'd consider 15% per week to be at the low end of the range, especially if you're keeping messy fish like scats. There's an argument (which I subscribe to) that good quality water at a lower than optimal salinity is better than poor quality water at an optimal salinity. In other words, if the cost of salt is an issue, I'd expect a tank of scats kept at SG 1.005 to be healthier with 50% water changes per week than another tank of scats at SG 1.010 but only getting 15% water changes a week.
Anaerobic gases in the sand
-- This is alarmist. I have seen gas bubbles in the deep sand substrates I use in my freshwater tanks (for the benefit of the plants) and never had problems in the 10+ years I've kept fish thus. Moreover, deep sand beds are used routinely in marine aquaria to foster anaerobic decay, and anaerobic decay also happens in living rock. In marine tanks, this is seen as a way to convert nitrate into nitrogen gas. It seems entirely likely that because hydrogen sulphide is so reactive, that even if it gets produced in an aquarium, by the time it hits the water it is oxidised long before it has a chance to cause any damage to your fish.
Green Spotted Puffers
-- I simply don't believe these fish need marine conditions to live a good life. That isn't to say that marine tanks aren't a good place to keep adult GSPs; they may well be. But I don't believe they're essential. I agree with Frank Schaefer and Klaus Ebert that provided water quality is good, 50% marine salinity is more than adequate for them.